I've registered for DeveloperDeveloperDeveloper 4 on Saturday 2nd December. I missed DDD3 because I was on vacation but I found the first two were well worth attending.
From the DDD site:
This FREE one day event builds on the success of the previous DeveloperDeveloperDeveloper Days. As before it is all about developers learning, sharing and interacting with each other in an informal and relaxed atmosphere.
There will be NO Microsoft speakers presenting, just speakers from the UK .NET developer community; although we will have some of the Microsoft UK Developer Team on hand to help out and chat to attendees.
The day is put together by the community for the community, in other words you. With Microsoft UK very kindly providing the venue, logistic support and a free lunch.
Register here but be quick.