As of October...
...that was actually 300,000 apps. so about 6,000 great apps. I can't name 600 for the Windows platform.
Also note, The Apple app store launched in July 2008, Android only 3 months and 2 weeks later in October 2008. Apple has 300,000 apps, Google 100,000. Apple did not have a massive head start here, less than 15 weeks. Still, 3 times the number of apps, and the lions share (80+%) of money exchanged for apps by users. Devs like it there; very low platform fragmentation, easy to use interface, low startup costs, limited hardware versions to test against, nice emulator, good pricing policies, and more viable users.
Even if android had twice the devices in the field (which it does not), the number of people who can buy a specific app in the android store would still be more limited, smaller and smaller for the higher quality of the app. Many games run exclusively on the most cutting edge devices, which is a very small pool. More over, those games may sell great now, but in 6-9 months, those devices likely won;t be running the newer version of Android that new games are being developed on, and may never be upgraded to support them. Its both a small and short lived client pool, expensive to code for (3-5 times the man hours costs if you ask most companies), and has far lower profit potential on top.
GREAT apps and very modern games are coming to iOS in droves, and every one of those dev teams keeps saying "Android is on the back burner, maybe we'll suppoty it one day but it;s not ready for us yet."
Carriers are pushing the devices because of a lack of alternatives, but WP7 is going to get a lot of marketing money, and Apple keeps adding carriers and expiring exclusivity deals. If you want to play games and have the best cutting edge apps, iOS is where the money is, and that's were the devs will be. The larger this disparity gets, the harder the Android commitment becomes. The more people disgruntled by manufacturers failing to upgrade their devices making the latest android aps available to them, the more people that will never buy another device from that company. This is a cycle either Google needs to step in and stop, cold, or the platform will die.
...and I like Android, and am considering a tablet as soon as 3.0 comes out.