• by Gavin O'Malley , Staff Writer @mp_gavin, March 12, 2012

Stealing the spotlight at SXSW on Sunday, Instagram said it has surpassed 27 million registered users. More remarkable, the photo-sharing startup’s user-base is still limited to Apple users. That’s about to change, however, as co-founder Kevin Systrom showed off Instagram’s upcoming Android app at the Austin conference.

Without giving a full demonstration, Systrom told TechCrunch: “In some ways, [the forthcoming Android app is] better than our iOS app. It’s crazy.”

Systrom didn't specify a release date, but says that he hopes to release Instagram for Android "really soon," according to The Verge.

Still, “While many Android users are understandably excited by this news, the reactions on Twitter tend to focus on how long it’s taken the Android version to be ready,” writes WebProNews.

What was the holdup? Systrom says the company has simply been too busy scaling on Apple’s iOS. “I don’t think it took us so long,” he said. “We just had priorities. Had we tried to be both on Android and iPhone at the same time, it would’ve been tough to innovate in the way that we have.”

Yet, some wonder whether Instagram has missed its window among Android users. In its absence, “Numerous competitors and imitators have sprung up trying to fill the Instagram void such as Lightbox Photos, PicPlz, and Vignette,” as Computerworld reports.

Meanwhile, without revealing overall engagement levels, Systrom said that among users who were active in the last week, 67% used its app on Saturday. “It’s Facebook-level engagement that we’re seeing,” Systrom told TechCrunch.

Another gray area for the company is its business model. As TechCrunch notes: “The app currently doesn’t have any advertising and it doesn’t have any in-app purchases.”

Regarding the company’s monetization potential, co-founder Mike Krieger said: “We have a visual platform and advertisers like visual mediums. They like TV and magazines, but attention is moving online and they want to switch.”