I am not sure if this is 100% new in the UK or not. But it appears that from a Search Engine Watch Forums thread that moderator EvilGreenMonkey started, Google has now implemented Click-To-Call features in the UK.
A search on jet2 at Google.co.uk brings up this ad.

If you click on the green phone icon, it opens the ad up to enter your phone number;

I am not sure if they launched this in the UK before, but I believe they haven't. This has been launched in the US a while back. Hat tip to Sami Kasap.
Forum discussion at Search Engine Watch Forums.

Comments:
rxbbx
09/04/2006 02:30 pm
indeed.. did not see this in UK and rest of Europe.. it's always a pity that europe follows that late with new things.. we always have to wait.. :(
SEOer
09/04/2006 02:41 pm
This was actaully launched about 4 weeks ago
evilgreenmonkey
09/04/2006 03:48 pm
"This was actaully launched about 4 weeks ago" Are you sure that this was on Google UK? Do you know which search term you found it on?
Devil's Secret
09/05/2006 05:47 pm
Yes!! I'm in the UK and I saw it... Works fine..!!!