It's the 24th, not the 17th.
"next Saturday" seems to be ambiguous - I'm used to using "this Saturday" to refer to what would today (14th) be the 17th and "next Saturday" for the subsequent one on the 24th, but it looks like not everyone shares that usage. I could spend some time on it this weekend but I don't want to commit to it because it's hard to estimate how long it will take or how much time I'll have.
An email from David Wood, organiser of the Humanity+ UK 2010 conference in London on Saturday 2010-04-24:
I plan to make such a poster, and I'd like the advice of people here. Trying to represent what Less Wrong is about in the space of a poster could be challenging. I have maximum space equivalent to sixteen A4 pieces of paper. In the spirit of not proposing a solution until you've had a chance to think about the problem, I'll put my current plans into a comment.
Update: looks like it will be Roko rather than me making the poster, but the same applies, your ideas could doubtless be very useful!