I have a brand spanking new 27" imac, and I shut down every night. I noticed that when I start my imac in the morning, sometimes I get a progress bar so it takes a while before I can login. Then the screen comes up, but I get that empty wireless semi-circle and it says that there is no wireless hardware. What the heck. Come on Apple - this is your hardware and your software!!! And it can't be the routers - I have everything on Airport and Airport express. I'm seriously thinking about switching back to Snow Leopard if there is a way to cleanly revert back.
However, I might be still screwed on getting my Enemy Territory and Punkbuster to work on Lion. ET is not a PPC app, and there is some sort of issue with Lion where it deleted some files in the Application Support folder. Anyway, that's another issue.