Last month, mobile web requests via Wifi represented 8% of all mobile web requests. 19% of all mobile web requests were made by Wifi-enabled devices, up from just 9% in August.
Apple's iPhone and iPod Touch dominates the field of total Wifi requests at 78%. In fact, 42% of all web requests from the iPhone are generated on Wifi. But keep in mind that the G1 was just released in the middle of October and one month later was in the top 10 of devices accessing via Wifi. It already represents 7% of total T-Mobile traffic. The Blackberry Bold hasn't cracked the top 10 (yet) but is also a relatively new phone.
Another interesting note is that Sony's portable gaming device, the PlayStation Portable (PSP), generates 13% of all Wifi requests for the mobile web. It's not the only portable gaming device that is Wifi-enabled. The Nintendo DS can access Wifi, but it's not showing up at the top of these lists.
You can download the entire PDF report here.