I'm testing out various brands and classes of microSDHC to see which actually perform as they should and whether the microSDHC or the gumstix data bus is my write speed bottleneck.

http://fastr.github.com/articles/testing-file-write-speeds.html

So far I would recommend Kingston. It's more expensive, but it performs well. I should have a class 10 of theirs soon to test against.

AJ ONeal