I have also had this problem with several Logitech mice, including the performance MX I fixed mine by desoldering and replacing the left microswitch with another (stolen from another, broken mouse). This is reasonably straightforward if you're comfortable with soldering, it just requires quite a lot of disassembly to get to the underneath of the logic board. Alternatively, and much more simply, you can try opening up the microswitch and bending the internal spring back into shape. This is described in detail here (not my video). Hope that helps
Before the 802.11n draft was ratified, Apple had quietly been introducing the "draft n" hardware for a few years, enabling the functionality later through a driver update (source). Let's hope they have had the foresight to do the same this time around. Hopefully the teardown will reveal wi-fi hardware choices. Judging by the pic of the new MBP internals on Apple's site, it does look like the wireless components are on a removable daughter-board, so there may well be the possibility of an upgrade (3rd party or otherwise) in future.
If the button has failed altogether, you can also use RecBoot to put your phone in recovery mode. Like Brad says, while in recovery mode, if you unplug it, it will turn off after a while. To turn it back on, plug back in and use RecBoot again to bring it out of recovery mode. Not exactly an everyday solution, but should work if you want to take it apart without having to run the battery down completely. :)