I am quite happy to invest my time learning Android. Apple has taken Microsoft's place as the biggest bully on the block.
Microsoft seems closed and bullying next to the FS/OSS communities, but its success among proprietary vendors has traditionally been a result of its relative openness - to hardware platforms and devices, to third party developers, to add-ons and plugins and even competing products.
Sure, they threw their monopoly power around by bundling applications with their OS, but it's not like they actively prevented third party developers from making competing products available.
(Obligatory aside: I'm no Microsoft apologist. I had been replacing proprietary software with open software on XP for several years, and when it came time to replace my PC, Vista was so bad that I finally made the jump to Linux. Likewise, I'm holding out for Android before investing in a handheld device.)
Apple, by contrast, has always been fanatically controlling about their products. They ship slick, highly refined products, but the flipside of that obsessive attention to detail is an obsessive need to control how you use those products.
The App Store is just business as usual: Apple exercising its customary full-spectrum vertical dominance of the entire hardware/software stack.
The market share is VERY small at this point, but that also means less competition, likely. The bigger mobile app companies are starting to release Android apps, and it seems like a pretty good time as well, as more carriers are planning to release Android-powered phones.