Nominet are releasing the previously reserved 2 letter domain names (e.g. aa.co.uk to zz.co.uk and some other “.uk” domains, such as org.uk and net.uk, this process has just entered the stage at which anyone can apply, some domain names having already been reserved by people with trademarks. Probably a fair few will go to auction, as I suspect some speculators will apply for all of them just to pick up those which remain unchallenged.
Zynet (my employers) are one of the registrars taking part, although interest has been pretty limited, I suspect because no one knows it is happening.
Anyway check Nominet’s site, and if you want to register contact ZyNet ASAP (before June 15th).