I just picked up one of these cards to act as a media drive for the MacBook Air.  I have a lot of media — mostly pictures — that I did not want on the SSD, as it’s only 128GB. While I was in no risk of running out of space on the drive, I wanted to effectively add another 50% to the storage on the machine, and the SD Card only sticks out only a wee bit, so it’s no trouble to leave it in the machine while I bang about town.

It’s advertised as having a 15MB/sec transfer rate, but I’m not seeing that — depending on what it’s moving, it’s between 8-10MB/sec. Downloading from it is faster, however, than adding to it. For small files, it’s pretty much instantaneous. For moving a gig or two of files, more like a 10 minute process.

You’ll have to swap it out, if you are loading files from a camera’s SD card, unless you load the pics through a USB cable from the camera, but it seems to work well. I haven’t tried, yet, to see if iPhoto and iTunes will store to it, but since I keep most of the photos out of the former program, it’s not normally an issue.

It’s a good, cheap solution for adding memory to the MacBook Air without resorting to a big USB memory stick.