How’s this for a deal?

For less than twice the price of a movie ticket, or dinner and a glass of wine, come see a top-notch production by one of America’s most distinguished playwrights. Offer reusable and good through 2011.

This may sound too good to be true, but it’s not. The Signature Theatre Company announced yesterday that, thanks to the support of Time Warner and a Signature trustee, Margot Adams, all seats for all scheduled performances through the 2010–2011 season will be $20.

In the same press conference, the Signature, which devotes each season to a single playwright, announced the lineup for its next four seasons. The 2007-2008 playwright-in-residence will be Charles Mee; he will be followed in 2009–2010 by Suzan Lori-Parks, and in 2010–2011 by Tony Kushner. The 2008–2009 season will be devoted, for the first time, to the artists and the work of a company, the Negro Ensemble Company. In addition, the final production of the 2007–2008 season, as part of the Legacy program, in which former playwrights-in-residence return to the Signature, will be Edward Albee’s “Occupant.” It was originally staged at the Signature in 2002, but the production never opened because its star, Anne Bancroft, contracted pneumonia during previews.

The $20 ticket initiative sets a standard of accessibility that other nonprofit theaters are unlikely to ignore. It also represents a very successful and enlightened partnership between a cultural institution and a corporate donor. At a time when some major corporate sponsors of the arts, like Altria, are winding down their activities, a few companies and foundations appear to be stepping into the breach. The Rockefeller Foundation, in particular, yesterday announced the creation of a new program to distribute $2.5 million a year to cultural organizations for innovative programming and initiatives.

The Signature, with support from Time Warner, had already been offering $15 tickets over the last year and a half, and yesterday’s announcement suggests it will make a permanent commitment to low price (or, as the Signature and Time Warner would emphasize, subsidized) tickets. The Signature’s artistic director, James Houghton, admitted that the company hasn’t actually finished raising the money to subsidize the next four years, but “we’re going to put it out there.” And while it won’t be easy to secure that level of support in perpetuity, after four years, how would it look if they had to jack the prices back up to $65, their normal price?

The effect that subsidized tickets have had so far should make other artistic directors take notice. Mr. Houghton said that the productions for which tickets have been $15 — Horton Foote’s “The Trip to Bountiful,” John Guare’s “Landscape of the Body,” and this season’s three August Wilson plays — played to 105% capacity. More than 30% of the audience was under 35, and half had never been to the Signature before. When tickets went on sale for the final play of the Wilson season, “King Hedley II,” there was a line down the block. Online ticket sales sold out in 45 minutes, and the entire run sold out within 48 hours.

The idea of Time Warner, a giant of the contemporary media and entertainment world, helping to sustain the tradition of live performance suggests a pleasing possibility: that of the major businesses of the 21st-century city vitalizing (rather than displacing) the cultural life that made New York City so dynamic and attractive in the 20th century. In an interview with the New York Sun last year, the vice president of marketing and arts development at Time Warner, Dan Osheyack, said that Time Warner’s arts philanthropy was guided by a real business need: to develop new audiences and new creative talent. Of the Signature’s $20 ticket initiative, Mr. Osheyack said yesterday: “This fits so beautifully into our mission, which is what we call ‘the democratization of the arts.'”

For a company with major film, television, and Internet properties, that is indeed a fine slogan. But for the performing arts, democratization doesn’t come cheap. As Mr. Osheyack said, “These are not discounted seats; these are underwritten seats” — underwritten to the tune of $45 each. Should other companies wish to follow the Signature’s lead in this area, will there be enough corporate or foundation money to go around? The departure of Altria, which last year made grants to 272 arts organizations, leaves big shoes to fill. Some major foundations are coming to the end of their run, too. The Peter Jay Sharp Foundation, a generous supporter of New York City Opera, the Juilliard School, and the Brooklyn Academy of Music, among others, recently announced a $1 million donation to City Opera, as the lead donation for a $2 million special projects fund for the new general manager, Gérard Mortier. But the Sharp Foundation is liquidating and will spend itself down by around 2012.

Fortunately, some other companies and foundations are stepping up their cultural activities. Last month, Deutsche Bank announced six $100,000 grants to a diverse group of cultural institutions, including the Bronx Museum of the Arts, Harlem Stage, and the Queens Museum of Art. And the Rockefeller Foundation has now created its arts fund, both to fill the breach left by departing corporate patrons, and to respond to what it sees as threats to New York’s creative edge.

A recent study, called “Creative New York,” which the foundation commissioned from the Center for an Urban Future, examined the impact of the creative sector in the city — both for-profit and not-for-profit — and its long-term needs. An associate director of the Rockefeller Foundation, Joan Shigekawa, said the report concluded that, due to factors like real estate values, the cost of health insurance, and other cities’ efforts to attract artists, the city’s creative culture “might be at risk if we [don’t] continue to innovate.”

Out of the New York City Cultural Innovation Fund, the foundation will award two-year grants of between $50,000 and $250,000 for projects that represent significant innovation in programming; creatively engage with the issues shaping the city’s cultural and civic agenda; bring cultural and community-based institutions into partnership with universities or the private sector; or address, and propose solutions to, the systemic challenges facing the city’s cultural sector.