I have been told that the android market will only show results that work with the phone browsing for the applications.
I do not know if that is true but almost all of the apps I have downloaded work, with the exception of a internet tv app that said my phone could not display in 480p.
The facebook app is just the profile page, the games such as farmville can only be accessed through the browser and only if you have 2.2 or a patched 2.1.