Every laptop in our company is a Thinkpad, there are NO wi-fi connections in the buildings, We use ethernet exclusively when indoors(1000M - its MUCH faster), and WWAN (with RSA keyfobs) out of the office. Now this maybe different for smaller companies, but large financial corporations aren't going to suddenly all move to using a new OS and wi-fi, because of the Air.
Also, the lack of a an easily removable HDD is a bit of a sore point. Our IT people won't even connsider a laptop without a removable HDD, for if they have to send a machine back to the manufacturer or dealer, they have to remove the HDD first, for security purposes (a lot of customer information on our machines, it's encrypted, but we're ultra paranoid.). I asked the IT guys why they don't just wipe the hard drives with a wipe program, they said it takes too long. removing a HDD on a thinkpad - less than a minute - wiping HDD - over an hour.