How many people are posting their actual battery times, and how many are just speculating on what the battery life is? (hard to tell from some of the posts.)
I have read different reports on this. Some people have said 2-3 hours, others have said 4-5. Gizmodo (or some big tech site) did a pure wifi test on the iPhone (reloading an web page every 10 seconds until the battery died), and they got in the range of 5 hours wifi IIRC. The Touch will be less, but if you were to scale based on the music and video playback times (which is probably a reasonable first stab at it), the Touch should still get pretty good results with wifi.
When I had a Touch with screen issues, my impression was that the battery would definitely last more than 2 hours, but I wasn't running any sort of test so I don't know how long. My main feeling is that the battery will last as long as you really want to surf on a 320 x 480 device in a day or 2. The Touch is great for here and there web surfing, but if I'm going to spend more than an hour or so actively surfing, then I'll probably be doing it on a regular computer instead.