SANTA CLARA, Calif. – First Apple rolled out its App Store, a mobile storefront where consumers can download games, social networking services and other software programs for their smartphones.

Starting Wednesday, Google will offer similar services through its Android Market, which coincides with the launch of the first Google-powered mobile phone.

Now comes Research in Motion (RIMM). The BlackBerry maker announced Tuesday that it too will launch a mobile storefront — this one dubbed Application Center.

“This is a new channel to market,” RIM co-CEO Mike Lazaridis told some 700 mobile developers attending the BlackBerry developer conference here on Tuesday. “The opportunity is larger than ever, from enterprise to consumer.”

Mobile applications have been around for years, but never gained traction until Apple started offering consumers the user-friendly, one-stop shopping App Store in July. Almost overnight, the race for consumer dollars — not to mention the advertising dollars attached to mobile software — was on. Apple says its customers have downloaded more than 100 million applications to date. Now companies like RIM are scrambling to compete.

The three stores, while essentially similar, have some key differences. Unlike Apple (AAPL) and RIM, Google says its applications will be available for free. RIM will take a 20% cut of the revenue generated from download fees, while Apple pockets 30% of its developers’ revenues. Also, Apple and RIM must approve software applications before they can be sold — a level of control that critics say should be left to users, not the companies. Google, meanwhile, insists developers can sell any programs they want through Android Market.

This isn’t the first time RIM, the leader in the U.S. smartphone market, has gone after Apple. The two companies became rivals when the iPhone launched last year, but it didn’t get serious until Apple started courting BlackBerry’s business customers with the new high-speed iPhone 3G and App Store. RIM, for its part, is now chasing after Apple’s core customers – tech-savvy consumers – with flashier devices that emphasize multimedia and social networking features. The Canadian mobile device maker plans to launch an iPhone-like touchscreen device called the Storm later this fall.

But the iPhones assault and some unexpected product delays are worrying RIM investors as the crucial holiday season nears. “We believe the next 30-45 days are a critical window for RIM,” Citigroup analyst Jim Suva wrote in a recent report.

And while Apple and Google’s (GOOG) application stores are already live, RIM’s Application Center won’t be up and running until March 2009.

Still, RIM’s 31% share of the U.S. smartphone market will be hard to crack. Apple trails in fourth place  — behind HTC and Palm (PALM) — with about 12%, according to Nielsen Mobile. But RIM isn’t alone in its pursuit of Apple. Samsung, Nokia (NOK) and just about every other handset maker is now looking to catch up too.