Since I upgraded to OS2008 I have noticed that I don't get the same signal strength I used to. I used to be able to see APs down the street. Now I lose the one over my head. Any ideas?

Did you check your power settings under connectivity?

I don't have a power settings option. If you mean idle time its set to unlimited, but that wouldn't affect the radios severally crippled sensetivity

there's an advanced option in the connections which allows you to choose 10mW or 100mW

the whole network connectivity stuff is like a maze of twisty passages all alike!

that's just transmit power, though, isn't it? Wouldn't affect detection of networks, I think?

Check this thread
According to a message from Nokia several months back, the 10mW/100mW setting shouldn't be an issue at all. The 10mW setting is only for those countries where there are legal resons for not using 100mW. Dropping to 10mW won't even help on battery usage, as the data is sent in bursts anyway (if anything it'll make it worse).

What you should look into in that section is the timeout settings.

It's possibly the timeout setting (the power saving mode). I'm aware of only one free hotspot in my town which has the timeout problem, and when the timeout setting was set lower (as in the newer versions of OS2007) I don't see that router at the initial scans, it does show up after a while sometimes (but I can't connect).

However, if you upgraded from the latest version of OS2007 to OS2008 (or from an earlier OS2008) then you shouldn't see any difference. If you did then this could possibly be something else entirely.