When you work on an Open Source project most of your communication with colleagues will be through the mailing list or maybe on IRC. This works great 90% of the time but I think everyone understands that occasionally it's really helpful to meet and talk to the people you work with. Traditionally this has happened at conferences, for example ApacheCon, EclipseCon and so on.
That's fine for people that are established committers - but what about people who want to start? Those mailing lists are pretty intimidating aren't they? Then when you do screw up the courage to write a note sometimes it never gets answered and you don't know why not. Or sometimes people don't read your question properly and answer something else. It can seem very unwelcoming. Initiatives like GSOC do a good job but they also miss the face to face element.
It was just because of this that we decided to run Open Source Jumpstart. We wanted students to meet committers face to face, just once. It's amazing how many of those getting started barriers can be broken down with one day's work. It would be great if any of the students from Saturday carried on working on Open Source projects - however, even if they don't, in that one day's work bugs were fixed in every project and students learnt about how code is developed.
There isn't much that's more satisfying than bringing two groups of people together and seeing both of them get something out of the experience. Have a look at the Meetup to see feedback from the event.