John_Ryan asked what board you have selected in the Arduino software in the Yellow Jacket thread??? You should select the "Arduino Duemilanove or Nano w/ ATmega 328" board.
I had an intermittent problem with my BW, which I cannot reproduce tonight, where I could not upload a sketch to the board (only tried at that time with Mac OS 10.6.3). I tried both Mac OS 10.6.3 and Win7 (on the same MacBook Pro booted via Bootcamp) tonight and I could not repro under either OS. In my case plugging/unplugging it several times always made it come alive. One symptom that I had was that the port would either not show up in the list of ports or I would get two blank lines in the list of ports; once I was able to see the the BW in ports it would work fine.
When this was reproducing it was in a warmer locale (70-80 degrees F) versus the current 65 degrees F. I was also using the BW for some programming at that time whereas tonight I am just plugging/unplugging it (so the board has not really had time to "warm up"). My issue could be a bad solder joint, dunno.
In my case this evening the L LED blinks 7-10 times and the blue connection LED never blinks - but I don't have a WiShield app loaded on it so it never even tries to connect. Have you ever been able to upload a WiShield sketch to the board? If not I am surprised that the blue connection LED lights up at all.
Now its time to confess and let us all know what deviant things you have done to this board

As always, the more details that you can provide the better help you will receive!
Greg