I bought one at Amazon.com (the 6GB) and the adapter came from a 1GB microSD sandisk that I bought at Office Depot (or was it Office Max?), a few blocks from where I live. They're both Sandisk branded, nothing special about it, they came in their original Sandisk packages, which is almost impossible to open. One of these also came with a USB reader, which works perfectly as well.

The 6GB is formated vfat, I've formated it jffs2 but for some reasons it didn't quite worked the way I wanted, so I finally reformatted it back to vfat. But it worked out of the box, without any tricks. I use it every day, the speed is satisfactory for a pda.

I haven't tried a 8GB because they were not available at the time I bought the 6GB, but I've heard the 12GB are coming, so I'll snag one up when they'll be out; I'm sure it'll be working just fine.

I might use ext2 next time, rather than vfat, but either way works fine anyway, no biggie.