I'll have to be the dissenting opinion here and vote "wait" depending on what you want to use the unit for.
Official firmware is still flakey at best. Now that part of the source is out, the homebrew firmwares are picking up, but I'm not sure if any of them are "production quality" yet.
Mainstream console emulation (NES/SNES/Genesis/Sony), which is what I'm in for, is still in the very beta stages (with the exception of Reesy's DrMD genesis emu). That's not to say it's not good and that Squidge, Zodttd and Fishybawb arent' busting their humps. They're doing great work (especially Fishy. His has to be the most frustrating since there are already two NES emulators that were apparently abandoned halfway).
Waiting a bit longer will let you get in on the next hardware revision (even if the specs don't change, the manufacturing process will improve), and give the homebrew firmware writers a chance to tighten up thier stuff. And if you want emulation, the longer you wait, the better it will get.
My .02, flames to /dev/null