To put this into perspective: The MBA Thunderbolt has 10Gbps upstream (1 channel) and 10Gbps downstream (1 channel). Anandtech mentioned that a 27" Thunderbolt display needs about 7Gbps of upstream capacity, which still leaves plenty of bandwidth for other things like e.g. Gigabit Ethernet (1Gbps), Firewire800 (0,8Gbps) etc.
Biggest limitation is that you can only connect one external display to a MBA, which is not only due to the lower number of channels (2 on the MBA vs 4 on iMac, MBP, Mac mini), but also simply because the graphic solution inside the MBA (Intel HD 3000) supports only 2 displays, one of which is the internal Notebook display.