There's now a group in Google Groups called LW Helsinki, it's a closed group so you'll need to request a membership. I'll soon put a short description about this in the LW wiki together with the group's e-mail address. I'm not too familiar with Google Groups but I understood that it can basically be used as an e-mail list (probably with some fancy extra features). It also saves all sent messages for later viewing, i.e. new members on the e-mail list can easily catch up on past discussion.
Short summary for Helsinki LWers: click here and request a membership.
Where: Café Picnic, Yliopistonkatu 5
When: Friday May 13th, 3 PM.
Less Wrong poster Patri Friedman (patrissimo) is coming to Helsinki on the 13th to talk about the Seasteading Institute's work. We're holding a meetup on that day, where he'll be attending.
In all likelyhood, I'll unfortunately be unable to attend myself. However, at least Bongo has promised to attend no matter what, so at least he and Patri will be there.