What exactly happened and why still seems to be extremely obscure, and I won't speculate, because it seems that some earlier speculation was wrong. But it does seem freedom of speech in the UK is being threatened in a new way with servers being taken down simply as a result of requests from US authorities.

http://uk.indymedia.org/
http://jebba.blagblagblag.org/index.php?p=115
http://jebba.blagblagblag.org/index.php?p=114
http://www.theregister.co.uk/2004/10/11/home_office_fbi_mlat_request/

It's good to see that Richard Allan MP has tabled a question in Parliament about it. Though one can easily predict the kind of uninformative answer he will get.