But Amazon doesn't seem content sticking to music downloads, given rumors of their upcoming Android app store. And while it will obviously be competing with the Android Market, it's still a huge vote of confidence for the Android platform since Amazon obviously believes it's a viable financial option.
The big difference between the two app markets seems to be the vetting process. Google has taken a very hands-off approach, which doesn't take any action against buggy or questionable apps until they are flagged by users. Amazon plans to spend a week or so vetting potential apps before releasing them.
Amazon seems to be doing the right things to gain a foothold in the Android app market, but until their app store actually launches we're all left to simply speculate on what app the future will hold.