Life – according to a German mobile-telecoms giant with access to your personal call data – is for sharing. But, at 30p per picture message, they would say that.

The cost of sharing pictures by text might help explain the effervescent rise of Instagram the (until now) free iPhone-based photo filter/sharing app, which adds one of 11 hip-looking digital filters to your point-and-click phone snaps and allows you to instantly share them with your friends. Or the entire world, via their own network or plugged-in social networks such as Twitter.

It's something that's very handy if you're documenting, say, breaking news, or the eating of a really nice pizza. But one to be very careful with if you're in the habit of sharing quick snaps of yourself in your Lacy Unmentionables to a partner.

Instagram's success is possibly less to do with its sharing capabilities, than its abilities to make normally maladroit camera-phone pics look genuinely quite cool.

Something it shares with Hipstamatic, the app that's had its own exhibitions and a war photo by Damon Winter which made it on to the cover of The New York Times and was nominated for a prestigious industry award. On Sunday, Kevin Systrom – one of Instagram's co-founders – told reporters at South by Southwest Interactive, the music festival's tech offshoot, that its application is now being used by 27 million iPhone owners.

Instagram also announced that it was to be made available on Google's Android operating system. In 2011 the Android system was on around 48 per cent of all smart phones sold (compared to Apple iPhone-only iOS's 19 per cent). So 27 million photo sharers is just the start for an app which has doubled its user base in three months.

As with all other free-to-use tech phenoms, the big question now for Systrom, fellow founder Mike Krieger and the various venture capitalists bankrolling the operation is how to make these free pictures make money. Which, for all of Instagram's charms, might be a harder challenge than having 100 million users sharing images of their cats and their meals.

Perhaps it's best not to follow the lead of the photography firm who encouraged us to "Share Moments, Share Life". That 2001 slogan from Kodak hinted at the limitless democratic possibilities (and massive oversharing) that digital photography could offer, only to be run over by other companies such as Flickr. Kodak filed for Chapter 11 bankruptcy protection in January.