funny you should ask....i just did this yesterday. Son bought the Marvel Universe (or close) game......had to upgrade via wireless. no cables needed, usb or otherwise (see, otherwise, then it's not wireless...
)
biggest showstopper...was when you set up config under "network settings" it asks all the questions....i made it easy (unsecured WLAN, automatic IP, DNS, etc. via DHCP)..basically entered the SSID and that was it.
BUT..........!!!!
You have to go to totally OTHER menu.......system settings, as I recall, and change default for wireless from "adhoc" (for psp-to-psp) to "infrastructure" mode...then it works!
Error you get if you don't do this step is nebulous........and you'll never find it out quickly.
should work fine then...and the game works now too!