to attend & willing to man a stand?
I'm going, but representing another project.
In the past it's been good - although numbers have gone down year on year seemingly, it's a pretty decent community meetup and the .org village is good.
This year, I believe it's being held at the same time as some Mac fayre. They did something like this previously, but with webmaster world or something, and it was a very successful year - lots of people who would otherwise not go to a Linux thing milling around.
In terms of preaching to the non-converted, it's probably a decent opportunity this year.