I think FOSDEM is a special event in that it's a real free software event - unlike LinuxThis or LinuxThat where there's some talk of free software and a load of marketing talk.
There should be lots of people from FSFE there, and Brussels is pretty easy to get to from a lot of parts of Europe, so if you're thinking of coming, I recommend it.
Talks this year include our own Georg Greve, "Beyond GPLv3": http://fosdem.org/2007/schedule/speakers/georg+greve
FFII's Pieter Hintjens on software patents: http://fosdem.org/2007/schedule/speakers/pieter+hintjens
Sun's Simon Phipps will talk about "Liberating Java" http://fosdem.org/2007/schedule/speakers/simon+phipps
And our Shane Coughlan will be giving a lightning talk on the FTF: http://fosdem.org/2007/schedule/events/51
And there's a load of other sessions that could be good: http://fosdem.org/2007/schedule/days
Wikipedia also has an article on FOSDEM, but there's not much there: http://en.wikipedia.org/wiki/FOSDEM