Just popped into the Sony shop on London's Tottenham Court Road and asked if they knew when the Reader was coming to the UK. They said they hadn't heard anything about it, but that products appear on the Sony UK website 2 months before they're released so to keep an eye on the site.
I've also signed up for email alerts about the Reader from play.com, who were advertising the Reader recently. Once I have any news, I'll post here.
If this is coming out in the UK, I hope it's by the beginning of July, because it'd make a great birthday present for me
Matt