Just spotted that Penguin UK is allowing unagented writers to send unsolicited email-only ms queries to them through August, September and October 2010.
So if you have something they might be interested in publishing, and you haven't yet netted an agent to do all the approach work for you, this could be your big chance.
You can find out more details on how to submit your work by email here at Penguin UK.
Good luck!