1.3Mbps
O2 UK 3G, about half signal strength indoors.
Not bad at all.......
Actually that's pretty bad for 3G in the UK.
The problem is all these speed tests are US based and are wildly off when used from the UK (they rate my broadband connection at about 1/3rd of its normal speed for example). There don't appear to be any UK based iphone specific ones but general broadband ones should be OK.. find one that gives the right results for a known speed eg. your broadband connection, then plug the iphone into it and see what comes out.
I was getting 7.02Mpbs the other day from work (good signal there.. also the only place I've ever seen an Edge conneciton around here when I had the 2G).
Even on my wifi connection it takes 12 seconds for bbc.co.uk so I'm not even sure that's a good test.. it's timing rendering speed at that point (my MBP over the same wireless can load it in under a second) - the iphone just aint that fast at rendering pictures that an individual website is going to help - you need to time continuous data transfer to show the difference.
It's a pity speedtest.net doesn't work on the iphone as that seems reasonably accurate from everywhere.
edit: dammit.. Can't get the numbers. At the moment there's not even any cell coverage around here let alone 3g data - walked for 15 minutes and 'No Service' anywhere. O2 really suck.