There will be an #XMPP #Sprint in #London from the 6th to the 8th of November at The Mitre in Greenwich.
From the wiki:
Sprints are a great opportunity to get to know the people you are usually working together with online. For people who are not working on XMPP full time they can also be a good opportunity to finally sit down and start working on that one project they always wanted to work on.If this sounds like the right event for you, come and join us!Beyond that Sprints are a good opportunity for inter op testing and bug fixing or in general a good opportunity to learn from each other. If you want to implement feature X in your client, another client developer, who already implemented that feature, might be there and can tell you what to look out for when implementing this feature.
Sprints can also be a rare instance where client and server devs are in the same room and a good opportunity to rapid prototype a new feature that has the client and server interacting with each other.