I have 10.5.1 on both my 12' PB and my 24' AliMac. Wireless on the former works fine, but now the wireless display on the upper right on the iMac shows only one wireless network at a time, even though I live in an apartment building, and there are usually about 10 visible. I can still connect to invisible networks, provided I know the name and password, so this glitch is annoying at worst.