The next Mozilla get-together will take place like every year in Brussels, in the FOSDEM's Mozilla room, on February 23 and 24.
There is a Fosdem 2008 Wiki page where you'll find more information.
FOSDEM is actually 2 events in one. First it's probably the largest Free Software and Open Source event in Europe, and it's totally free (of charge). It's messy, crowded, nerdy, fun and full of serendipity.
The main track room, photo by Anna Bialkowska, CC-BY-NC-SA
Second, Most large FLOSS projects (like Mozilla) have rooms there, where their contributors meet and work for 2 days. These rooms are open for everybody, so it's nice to meet in person with other contributors, but also engage with people working on other projects.
The Mozilla Developer room at Fosdem 2006, photo by Paul Kim, CC-BY-NC-SA
Oh, and if you need an additional justification, you can just pretend that you'll visit Brussels and will do some beer-tasting. Brussels offers many samples...
Mozilla beer tasting on Friday night, photo by Martin Creutziger, CC-BY-NC-SA
Now that you, dear reader and Mozilla contributor, are totally convinced that you should go to FOSDEM, you should register yourself on the Mozilla room Fosdem 2008 wikipage. Should you be interested in getting sponsorship to get there (travel and hotel), please say it so in the Wiki and contact Anne-Julie Ligneau (ajligneau -at- mozilla-europe.org) about this, and we'll see what we can do for you. Of course, we're looking for people to do some talks in the Mozilla room, so if you feel that you could share some knowledge with fellow mozillians, please get in touch with Brian King, (brian -at- mozdev.org), as Brian has a few slots available. See you in Brussels!