There are several channels that can be used for promoting a KDE event:
Identi.ca/Twitter - Leverage existing KDE related Identi.ca and Twitter groups.Here are some known groups:
LinkedIn - This networking service for working professionals has several linux-related groups. These have very substantial numbers of members in many cases. You start "discussions" once you've joined a group. These discussions get aggregated and sent out in an email notification to all the members. Here are some existing KDE related groups you can join:
Facebook - Another great social networking tool for spreading awareness. Like LinkedIn there are KDE related groups out there. You can also send "invites" to events, utilize the status updates to pass along news, etc.
There are many KDE related IRC channels out there. Another method for raising awareness about an event is to log in to these channels and get a discussion going about it. KDE IRC channels can be found at http://userbase.kde.org/IRC_Channels.
If possible try and get some other people helping with promotion to join in prior to mentioning it so there are at least a few people to help carry the discussion.
It goes without saying that the more people that blog about an event the more you can raise awareness for it. In particular, look to high visibility community members who are attending to help in promoting the event. Shoot for a mix of blogs that are syndicated are the Planet along with blogs that our outside the internal KDE community to reach a wider range of potential attendees.
Another great way to build interest in a KDE event is by building a list of relevant contacts and inviting them personally. This could be specific individuals (i.e. press contacts, etc) or other linux groups. Contacting Linux User Groups (LUGs) or distribution specific user groups is a good way to reach a big group of potential attendees as well. Some good starting points are:
Things to consider-
Consider putting together a survey for attendees to fill out. Provide it to them on the first day as other commitments may prevent some attendees from staying the duration of the conference. Questions could focus on various topics: