I posted a similar question the other day and no responses so far. But I bought an SXDC and will test it next week. If it doesn't work I'll just use it in an iMac instead...
I was able to test my 64GB SDXC card today on a Macbook Air 13". I was able to view and transfer photos and movies to iPhoto, as well as access files directly via finder. I played a movie directly from the Card as well on QuickTime. Everything worked well. I only had a few gigs worth of data on the card, so not sure what might happen if the card was full(er).
I was able to capture a screen grab from System Profiler, which you can view here
http://tinyurl.com/29drg9y .
Nice! good to know, I just got my MBA (it was a X'mas gift) & i was planning to do some light DV work on it. I was thinking of getting the Final Cut Express & the Canon HF M32 which supports SDXC. This way I can just work with the USB & not get hung-up of the lack of firewire...meh 😉