The main concerns for me currently on the Air have more to do with the hard disk and lack of expandable RAM. The SSD would be nice, but is just too pricey, and not quite better then hard drives in all regards. The tiny 1.8 inch drive is a step back in speed, and capacity. As a secondary only system though, 80gb would probably be more then enough. 2GB of ram seems decent, up till you start thinking about virtualization. I'm finding more and more use for it at both home and work, so more RAM is always good.

The lack of an optical drive doesn't bother me at all. Again with it being a secondary system, if I do need to rip a CD, encode a DVD, or install software, it can all be done on my main machine. I don't back up to optical discs, I don't use them for storage, and I rarely even install anything off them beyond the core OS.

Ethernet, I'm mixed about. A secondary system probably wouldn't have a huge need for wired connections with what I do. Wireless at home, work, and at pretty much every business and hotel I've been to recently means no need. But I can understand for that one time you do need it, having it right there instead of on a dongle would be nice.

Odds are though, the Air will be my next laptop, as I've transitioned back to having a desktop at home. My MacBook Pro has a while to go though before I feel a strong need to replace it.