The AT&T Tilt in the UK, with an O2/UK Pay as you Go sim card... report
 

Well, the trip to the UK is winding down. The tilt's been working great for me. I got an o2 sim for it before I left (ebay) and a 20 pound voucher (ebay.uk) - she was working when I landed ;)

Didn't actually put many minutes thru the thing (incoming calls free, bulk of my calls were incoming) but voice and sms worked fine - still have some credit left on the sim after nearly a month! Didn't use data (specifically set the connection options such that data access failed) but did rely heavily on the GPS (TomTom6 + uk map) which worked flawlessly. Did several Quick GPS updates via wifi while here (was here for nearly a month!) and didn't got anywhere without gps enabled. Was using a vent mount and car power adapter which all worked very well.

Anywhoo, in case anyone is planning on roaming the globe, looks like the Tilt is a reasonable world phone.

Oh, and yeah, I had to unlock the phone to accept the O2 SIM. AT&T would not give me the unlock code since I had not had the phone for 90 days (stupid them, its a business account with a 2 year contract, DUH) but was able to do it following the procedures and special radios over at xda with ease...

Re: The AT&T Tilt in the UK, with an O2/UK Pay as you Go sim card... report
 

I just got back from the UK tonight and was using a Tilt also. I had TomTom 6 and it worked well when I used it. I was using a T-mobile pay as you go card with the everyone plan. I was there for five days so I signed up for their 2.50 for five days web and walk plan. I also signed up for a yourcallworld account for the 3p per minute to the US calls. I had a LOT of time on the phone and don't think I spent more than 25 pounds for the time, data and everything. Used the Tilt to tether my laptop a bit also.

I second using this device for traveling.