I have seen it mentioned that MicroSD + adapter has been shown to be working btu I don't have the reference
This microSD card + adapter works with Arch:
Some googling suggests that the MMBxxxxx marking on the back means it's actually made by Samsung, but I have no way to prove that.
There's some more images of cards I've proven to be working in a Pi here http://selsinork.imgur.com/
I've added them all to the wiki and will continue to do so as I'm able to test more.
I have some 8Gb class 10 cards ordered, including one UHS capable one, they should be here in a couple of days and I'll post another msg with results.
The comment about microSD cards not working seems to be something to do with Fedora, but I can't find the original mention of it.
Unfortunately it's now been parroted so often that it's taken on a life of it's own and become an absolutely irrefutable urban myth