You can contact us at info@fosdem.org.
During the event, the infodesk is reachable through +32 2 788 74 74 (only for urgent matters).
There's also a mailing
list (archives)
available to help you find accomodation, transportation, etc. with other Fosdem visitors.
This mailing list is for people interested in the Open Source & Free Software Developer's European Meeting. If you are looking for a lift to come, or if you want to be updated regularly, subscribe to this list now! :-)