Yes, I know the thread is old, but I found it while searching for information about these lovely little ones.
I have a bunch of Attiny85 and not even all Arduino sketches works on them. You need to fit all code inside the 8192 bytes available, there's no crystal to handle timing and so on. Maybe it would be viable if one were to create a separate Core library, strictly for these tinycases, but that's beyond me.