Ordering wine by the glass used to mean scant choices and bland options.

SAN FRANCISCO — Ordering wine by the glass used to mean scant choices and bland options. And only your tastebuds would tell you how long the wine had languished in an open bottle.

That's changed, with restaurants amping up the volume on what's available by the glass and making sure that the wines poured are at optimal freshness.

"It's one of the most exciting times to be drinking wines by the glass," said Talia Baiocchi, U.S. wine editor at winechap.com who recently researched and profiled wine-by-the-glass programs at 30 New York City restaurants.

Why is wine breaking through the glass (serving) ceiling?

Reasons range from the economy — who has the wherewithal to spring for a bottle these days? — to an increasingly educated public not content with ordering the traditional "house red, house white," as well as new serving systems that keep wine fresher longer.

The result: "Restaurants have gone from being safe to being experimental," said Baiocchi. "It wasn't a place for the sommelier to necessarily show off their personality, which I think now it is."

Take the Prohibition-Speakeasy Wine Club in Healdsburg, which offers about 30 wines by the glass, rotating the wines regularly and including "cult" favorites such as vintages from Sonoma County's Williams-Selyem winery.

The club is physically inviting, guests enter the bar by going into a phone booth and picking up the phone, which opens the bar's "secret" door. But owner Richard Rosenberg says the wines are the real attraction.

"The public has become more interested in different wines and different producers of different varietals and there are more varietals available than there have been in the past. That's the intrigue and that's what the big draw is."

Prohibition uses a Cruvinet system which can handle up to 16 bottles at a time, keeping the wine fresh for up to 40 days.

Other restaurants are going to systems that can serve wine on tap, similar to beer delivery systems.

Kimpton Hotels & Restaurants, which has 55 restaurants and bars across the country, has launched a new Wine On Tap program. Emily Wines, master sommelier and director of wines at Kimpton Restaurants, (yes, her name is wildly apt for the job) is leading the draft wine program through a partnership with Free Flow Wines.

The idea is to provide fresh wine by the glass, strengthen relationships with local vineyards and reduce waste. No bottles, no corks, just refillable kegs, generally made of stainless steel or food-grade plastic, that use a mixture of argon and nitrogen gas to push the wine out.

"Every glass that we pour is just as fresh as the first one," said Wines.

It's a learning experience all round. Winemakers have been coming by restaurants to see how the wine is tasting and wait staff also are being educated on how to explain the wines. The idea is so new that in some cases winery officials have been dropping off and picking up the kegs themselves.

Among the winemakers working with Kimpton is Paul Dolan of Paul Dolan Vineyards in Mendocino County.

"The kegs are just amazingly fantastic," says Dolan, a longtime supporter of eco-friendly winemaking and growing practices.

At Frances restaurant in San Francisco, two wines are served on tap, with the blends, one red, one white, supervised by beverage director Paul Einbund, who works with nearby wineries to create the finished product.

Using a keg system means he can adjust the blend for the seasons, richer and heavier in the winter, lighter and crisper in the summer, as well as the elimination of having to recycle bottles and corks.

Customers get the wine in pitchers etched with measuring marks and are charged $1 an ounce. Which fits the restaurant's goal of serving as a neighborhood hangout as well as a destination restaurant.

Einbund, who previously worked at a 2-Michelin star restaurant, jokes that he's "super snob sommelier boy," but "I am so excited to have a wine that's a buck an ounce that is delicious."