The flash storage in one of our 2010 Airs, a 13-inch model with 128GB, stopped working properly before we were able to finish the tests. It failed three-quarters of the way through our final OS X installation task. We tried restoring from the included USB flash drive and from a retail Snow Leopard disc. No go. I booted from an external drive and used Super Duper to clone a working Air image, but it still failed to finish. I ran Disk Utility's Repair Disk on the flash storage, but it didn't find any problem with the drive. Other times, the drive would fail to unmount. Many hours were spent, but in the end we decided to risk the health of another new Air, the 256GB 1.86GHz 13-inch model referenced in the results above, which had no problem completing these same tests.
Seeing how three of the Mac flash drives made it through the testing with flying colors, I'll assume that the one that crapped out was a fluke. We'll keep testing and will let you know if this turns out to be anything more than that.
James Galbraith is Macworld's lab director.