My current employer, Net Communities, is looking for a Python / Django developer to replace me -- I'm moving to Oxford to work on a very interesting Django site. I can honestly say that Net Communities has been a fun place to work, and if it wasn't for the fact that I'd prefer to live in a smaller place than London, I would still be there. Net Communities is based in Farringdon, London. See the job ad for more details.
To filter out the developers who are bluffing, I have devised a series of programming tests, each more fiendish and difficult than the next. Actually, they aren't difficult at all. The tests are just some of the typical tasks that you might need to do for a Django site. You will be sent a link to the test if you apply.