This is a group about JavaScript so we should talk about all things JavaScript. How it's currently used in Websites, the various JavaScript libraries out there, AJAX, the ongoing 'Web 2.0' movement, the use of JavaScript in cutting edge websites and the future of the language and the websites that utilize it.
It won't just be about boring business use of JavaScript either, as JavaScript can be used to create very fun things too :)
I ended up choosing 'Tavern in the Square' which is right next to the Central T stop on the Red Line in Cambridge. Other technology meetups have used this and it seems like it will be a good location.