I did have the AirPort issue (dropping internet access while remaining connected to WiFi) with my mid-2010 MacBook Pro running SL. I sent it off for repair, and they replaced the Logic Board, but I still had the issue afterwards.
I managed to fix it by creating a network location, and its still working flawlessly to this day. I have no idea if this will fix it in Lion though.
I managed to fix it by creating a network location, and its still working flawlessly to this day. I have no idea if this will fix it in Lion though.