Chairing the EclipseCon Program Committee
First, I have to warn you that if Bjorn Freeman-Benson ever approaches you and says, "Hey, wanna chair EclipseCon? It really won't be much work..." you should turn and run. Fast.
Seriously, it has been a lot of work, but also very rewarding. Bringing a program together is challenging in many ways - at its heart, it's a fundamentally large bit of secretarial work, because there are many submissions, different categories, possible tradeoffs (more short talks and fewer long talks?), and a myriad of small issues (such as not putting two talks with the same likely demographic at the same time).
The program committee also has to look at the balance of the program, which is challenging in other ways - you don't want all the speakers to come from one company, or just from a few projects, or to just represent developers. We looked at different constituencies (committers, users, member companies, IT decision makers, etc.) and tried to ensure that some portion of the conference program would appeal to each of them. We also looked at a balance of old, current, and new technologies, because not everyone has been to conference before or is new this year. Finally, we tried to ensure that a few "virtual tracks", this year focused on RCP and embedded tooling, provided a credible draw for conference goers interested in those topics.
Apart from the sheer difficulty of reading and discussing so many submissions (and it's still going on - we're currently working on the short talks), one aspect of the program committee that proved challenging was trying to increase community involvement. This year we experimented with using a Bugzilla-like approach to submissions, which included allowing anyone to comment and even to vote on their favorite talks, including asking questions of the submitters. Ideally we would like to continue empowering the community, including the ability to rate comments by others and search more easily by adding additional submitter (and maybe community-provided) metadata in the submission form.
I'm looking forward to EclipseCon (ok, in part because my job as program chair will be over ;-) and hope to see you there - I'll be on an open source contributions panel discussion, the final plenary session, doing opening remarks one morning, and participating in the WTP events. If the abstracts are any indication, there will be plenty to learn about!

