On the iPad, how do I tell what version of Mobile Safari I have?
The only way I've found Ross McNab's way was much better but sadly no longer works (thanks, Apple); Billy Moon's way works but is a bit awkward for one-off checks.

Another way to do this is to use an external website (there are plenty to choose from, just search on "what's my browser"), which will report my user-agent string back to me.

So for instance, these sites will report back to me that my user-agent string is:

Mozilla/5.0 (iPad; U; CPU OS 4_3_5 like Mac OS X; en-gb) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8L1 Safari/6533.18.5

...from which I can tell that I'm using Mobile Safari 5.0.2.