I am having week 48 and 1.1.2 OTB iPhone.I upgraded to 1.1.3 jailbroken,unlocked and activated.when 1.1.4 firmware released I updated and was victimized for wifi issue.
Wifi is not greyed.Wifi is on but safari/itunes/youtube cannot connect to internet.making or receiving call is fine.

Any Solutions ?

Bala

Remove any DNS IP Address in your WiFi settings and add this one instead ( 208.67.222.222)

Also, you can try to ping your iPhone from a computer connected in the same network to see if it is correctly connected.