2+ years of iphone dominating the smartphone market didnt prevent android from catching up.
I've gone on before about AT&T carrier-lock-in vs. the open market of tablets, like the open market for mp3 players (aka iPods) before it, so I won't do that again, despite the tremendous difference it makes. Instead I'll address "catching up."
I take it you mean all iPhones sold vs. all Android phones sold.
Not handheld iOS devices -- iPhones + iPod Touches -- where there are still significantly more than handheld Android devices. This is what matters to families who purchase apps, music, etc. under the same account, and what matters to developers.
Not phones that can run and install the current version of the OS with all its useful features, where 95% of iOS devices are but only 50% of Android devices are, so that nearly all iPhone users have the latest cool stuff (Airplay, etc.) and can run any app in the store, unlike half of Android users. (Google announced yesterday that they're finally going to do something about that at the end of the year or so.)
Not "caught up" in terms of quality apps released, or when they're released if they ever get an Android version at all.
Not "caught up" in the sense of a unified platform that developers can program to, rather than a continually-further-fragmenting bunch of screen sizes and other capabilities, keeping those developers away. (Google announced yesterday that they're finally going to do something about that at the end of the year or so.)
Not "caught up" in terms of financial or business success for the the companies that manufacture and support them, where companies like Motorola and their amazing Droids are in threat of closing their doors due to the small margins and high return rate of Android phones.
And not consumer satisfaction or brand impression, where consumers are significantly happier with their iPhones than those with Android phones.
Just total quantity of pure phone handsets sold, even at a loss and regardless of buyer satisfaction. It's true, in that sense, Android totally caught up. You get 10 (or more) companies manufacturing phones under a single OS brand (regardless of functionality, compatibility, or upgradability), all of whom are risking their futures with the hope of seeing the success Apple has had, add up all of the phones they've sold so far under that brand, and indeed they've sold more of those than iPhones alone.
Glad I'm not one of the companies in the cadre that together have "caught up."