Well I have sherpa and Imeem on my Hero. So, yes there is nothing (at ths point) to prevent you from installing any apk files to your phone, but I'm sure they are working diligently to stop that as I type this.
Also, I believe that the Copy-Protection thing is NOT the only reason the certain apps are not showing up right now. Recently, Developers had to log into the Dev console and accept a new terms of service to keep their apps on the android market. I think alot of developers have not done that including the moker and m:mafia bunch.