Compared to all the 13in thin and light wi/out an optical drive the MBA is the more better as it is using an intel SL line cpu which is more powerful than the SU line cpu you see in devices like the Samsung X360 and Acer Timeline but it also use more power with the C2D SU line using 10W TDP vs the SL's 17W TDp. The ion GPU is also more powerful than the 4500hd, but again worse on heat and battery life.
However, there is one exception to this, and that is the hard to find LG P310, which also has no optical drive. The LG does have the faster Intel P series of CPU, and its the only 13in laptop to use the more powerful Nvidia 9600 GT gpu. The down side is, it produces more heat that it should because of the pairing of a higher power cpu and gpu than normal in a device that size. It also weight .2 oz more than the MBA.
There is also the Sony Vaio Z, which weights the same as the MBA, but it also comes with more features, like optional blu-ray drive, option for two 256gb SSD and external optical drive, and a higher res screen. But, that has the slightly lower nvidia 9300gs gpu(but you wont notice to much of a difference vs the 9400m), and the intel 4500hd when you want to save battery power. Additionally, the newer models can support 8gb of ram for a 64bit OS use. Base models can be had for less or about the same price as the MBA and can get really price when fully optioned up with everything.
Not sure if Apple enables VT but you can enable via the bios or bios hack VT on both those devices to do improve productivity.