My Wi-Fi signal seems weaker, in some places I got all bars, I get one less now.
I just got the update this morning and had to leave for work, so I haven't played with it too much. Are you noticing an actual weaker signal (drop-outs, slower connection speed, etc)? Or are you just noticing that the signal indicator shows less bars?
Remember, the signal indicators for everything are arbitrary. There is no Mobile standard that says -50 dB is always 4 bars and -105 dB is 1 bar. These can be different from manufacturer to manufacturer, phone model to phone model. Now that you've updated there's not a good way to check this, but if you know someone that has an Inspire that hasn't updated invite them over and both of you go to the Testing Screen (Dial *#*#4636#*#* from the Phone Screen) and select Wi-Fi status to actually look at your signal strength in dB (It's the RSSI: line). If you're showing relatively similar numerical signal strength, then HTC just re-adjusted the Indicator thresholds. If not then the update may have jacked with the Wi-Fi radio.
Also a quick thing you can check is make sure you didn't click off the "Best Wi-Fi performance" option under your advanced Wi-Fi settings.