I just got my invitation to the Python language summit. I had planned on going anyway, so the invitation just makes it less awkward for everyone involved. The summit overlaps with the tutorial days of PyCon because, well, by definition if you belong in the summit you don't belong in the tutorials [tutorial instructors can suck it].
The summit is interesting because it is unusual* - open source events are usually open access too. The agenda is wide open and is roughly focused on standardization and the future, whatever that is. The invitees are the core developers of all the implementations of Python: regular Python (aka "CPython"), Jython (Java), and IronPython (C#).
I'm not sure what the purpose of the invites is, other than to convey weight. To make the list is to ask "who are the 50 people on the planet who would actually want to come?" Griefers and trolls would be bounced regardless [come to think of it, maybe I was invited because I have no compunctions about bouncing griefers and trolls] so perhaps the invitations are meant to discourage the well meaning but clueless. Every convention has at least a few of those - does anyone remember the "callable None" guy from a few years back? "well meaning but clueless" doesn't begin to describe him.
* It is not without precedent. See the the Reykjavik sprint. [my favorite bit from those posts "Cod jerky smells a bit like feet but tastes OK. Dried shark smells a lot like feet and tastes exactly like dried asshole."]