Is the dowloadable version up to date

with the newest update from iTunes (Sept 12 2009)?

Sorry, but newest update for what? Do you mean the Apple TV? That would be 2.4. If that is not what you mean, please let me know.

I have the latest ATV Flash (2.4). Before upgrading my Apple TV in order to update iTunes to the newest version, I just wanted to make sure 2.4 would still work. So, from what I understand, it is just iTunes that got updated and not the Apple TV OS. So I can safely do the Apple TV update in order to get the latest iTunes…?

Even though Apple release iTunes 9, the current Apple TV version and aTVFlash versions all still work fine. If Apple releases a new Apple TV software version then you will need to not upgrade until aTVFlash is upgraded as well. There are small rumors saying Apple will make the Apple TV compatible with the iTunes LP and Movie Extras soon, hence a 2.4.1 or something like that.