Do they speed up useful things, like gallery viewing, photo saving and searching the music library, or do they simply speed up copying large amounts of data to and from the card via a dedicated adaptor in a PC?
What is the point?
I'd be interested to know, since there seems to be a significant premium placed on it in the shops, but the only people with a view on the subject seem to be professional photographers with DSLRs to worry about.
Tom