I just pulled my card in my Touch to check. It is a Lexar 4GB SDHC Class 2 and I have never had a moment's problem with it on any version. I can't say the same for larger Lexar cards, unfortunately.
There is a "2" that looks sort of like an @ sign on the card, next to the "HD". I thought it was a class 4!
http://goldenusb.en.made-in-china.co...mory-Card.html