If you just want to run OS X on it, the current MBA is quite the capable little Mac. It does amazing in Windows 7 also... actually it's about twice the computer running Windows 7 64-bit Ultimate.
The problem with the current model is when someone needs to run both OSes at the same time running Win7 in a VM. With only 2 GB RAM, and 256 MB shared to the GPU, the MBA is just not the right tool to run a VM efficiently. While the MBA could be updated at WWDC, I still think a quiet update is more likely sometime around WWDC but not necessarily at it. I feel a C2D MBA with an Nvidia 320m could be released anytime. I would expect it to have 4 GB RAM soldered to the board and either 192 or 256 GB SSDs. It could be updated at WWDC if it gets a case redesign or has a 3G/4G wireless card in it... Apple would want to show off the new tech which would ultimately make its way to all Mac notebooks. I don't know why Apple hasn't added a Verizon 3G/4G card yet (I say 3G/4G because Verizon would provide backwards compatible but surely start branding for 4G). The other thing I see as a possibility for update at WWDC is if Apple finally adopts a hybrid drive strategy. Apple could make all of its Mac notebooks a lot faster by including 32 GB NAND Flash soldered to board to give all Macs speed quicker than SSDs for OS X and applications.
The possibility of an MBA with a Core i7 CPU and discrete GPU, as the rumors are suggesting, sounds amazing but seems like a 2011 MBA to me. There's also the possibility of next generation Core i7s to show up in the MBA with only the GMA HD for graphics. Would you need an Nvidia GPU or a discrete GPU or would you be happy with the Intel GMA HD? I am starting to ask people if they would be happy with Intel's GMA HD as a sole graphics solution. If enough people would find it acceptable, it's more likely Apple would do that.
I think waiting for the next 13" MBP update would prove very worthy. Intel is making better Core i-series CPUs, and Apple will be forced to go with a discrete GPU in the MBPs once it switches to Core i5 in the 13" MBPs. I would think anyone that needs a Mac now should buy a plain MB or lowest price capable MBP for their needs, and anyone that can wait will find a much nicer MBA or 13" MBP early in 2011. Intel stops making C2D CPUs at the end of 2010, so pairing the Nvidia integrated GPU will no longer be Apple's "out" around Intel chipsets.
I hope for everyone's sake here that you have a chance to buy a new MBA with the rest of us to a newly announced MBA at WWDC. I am trying to be positive, but Apple has a lot of priorities for updates. It wouldn't be like Apple to update ten products at WWDC, but they truly NEED to update 10+ irrelevant products... 30" ACD, Mac Pro, MBA, Mac mini, iMacs, AppleTV, TimeCapsule, iLife, iWork, iTunes, their "Pro" apps, and iPhone.
