Excellent find Andy. I've just installed TBird on my Corsair USB 2Gb device, got it set up with 2 IMAP accounts and 3 POP accounts, and it works great, and best of all, no fingerprints anywhere on the PC I'm using.
Now if only the computer I'm using had USB2, it might be a little quicker!!
Flash memory and USB sticks are getting dirt cheap, and I can see theres a rosy future for portable applications like these. I use these USB devices all the time anyway to store data like documents, pics, and software.