Well the OSX 10.7.1 update is available now, and it purports to have addressed the WiFi issues, among a few other items. It’s a very small update in terms of size.
I have made the update on two desktop machines, an iMac and MacMini, and tested WiFi. It was quite a struggle to get the iMac to connect, but eventually it did, after resetting the Airport as well. Perhaps the problem was with cached files – hard to tell. The MacMini initially refused but on a second attempt connected to another Airport – one that had not been reset.
I have not yet updated the MacBook Air again to Lion. I want a bit more experience with the update first. There is no Ethernet fallback connection mode on the “Air”, and given that we use it around the B&B it constantly has to reconnect to one of our 7 different bases – something that should be seamless, but maybe not….
OSX 10.7.2. is already in beta testing and it seems targeted to a much broader range of fixes and some additional functionality. Overall I recommend continuing to wait before taking the plunge.