Late last summer, we wrote about what we considered to be the 10 best iPhone apps for photography. Instagram didn’t feature on that list, for one very good reason. It hadn’t yet seen the light of day. Doubtless it was a bit more than a twinkle in its developers’ eyes, but the general public had yet to welcome its picture-sharing prowess onto their operating systems with open arms. Now they’ve had the chance, there’s no stopping them: it took three months to reach 1 million users; and six weeks (yes six weeks) after that, it has a decent-sized city of users at 2 million.

When you consider that Instagram is available only on iOS – not Android, not Blackberry, not anything else – that’s, well, astonishing. So now the question is, will they be releasing an Android-or-anything-else version?

PicPlz has been making in-roads into the Android instant-photo-sharing market. Are we set for a explosive battle for dominance, or a growling detente with a division of the spoils?

(Headsup to TechCrunch.)