Looks like Lightroom 4 will be a worthwhile upgrade when it appears later this year.
You can preview the new functionality yourself by downloading the beta from Adobe.
For me the biggest changes are the new develop settings layout, soft proofing for your different printer profiles and the map function will become of interest when more cameras contain gps circuitry.
On a more “Ed Reardon” note Adobe have “kindly encouraged their programmers to get their fingers out” and burning images to DVD is now supported in the 64bit version of Windows 7, something they should fix in Lightroom 3 but have not.
UK upgrade price will no doubt be the same price as the US plus a special supplement to pay for a new Adobe executive aircraft.