i've just got it to work, you need to get the overlay form PocketGPSWorld.com
I've copied a little howto over here to make it easier for you
You need to register as a member (see the Members Area section on the left- £2.00 for a months membership). Then go to the Speed Cameras section and choose Download.
To download the GPSR map just select 'Garmin' from the SatNav System dropdown box, then 'GPSR Map Overlay' from the Camera Selections dropdown
If you follow that you should end up with a zip file containing a single .msi file on your system. Running the msi file installs the map into Mapsource so you can then copy it down to your 2610 like any other map.
You need to reload the existing maps as well as the new one.
In Mapsource, choose the City Navigator maps from the dropdown box, (top left box, says something like city navigator europe v7) then click the maps you want to d/l with the Map Selection Tool in the normal way. Don't send them to the GPS yet! Now, select the speed cameras map in the dropdown box, click on the UK and/or Europe map with the Map Selection Tool. This adds these maps to the ones you have already selected. Now, you can send the whole lot to your GPS.
Once its fineshed downloading to the gps (and its re booted) press the menu button twice on the gps then select map info, you should have city navigator and another map called euro poc, thats the speed cam one. if you go to map view and zoom out there should be loads of largish green dots everywhere
I can't get it to warn when i'm near a speed cam yet but i've dug the manual out to have a look to see if it's possible