I just want to caution folks that whoever did this using this "Meredith" account is not necessarily (and most likely is not) Meredith, the person. It's much more likely that a hacked account would be used to do something malicious like this.
http://www.meetup.com/San-Francisco-Startup-Pitch-Night
http://www.meetup.com/Chicago-Startup-Pitch-Night
http://www.meetup.com/New-York-Startup-Pitch-Night
She's also a member of multiple meetup groups in NYC, so my guess is that she's likely a real person who lives in NYC, but just happens to want to be an admin for other meetup groups in random cities.
This was found by simply doing a reverse image search of her profile picture on google images.
She also the organizer of Startup Pitch Night, which explains her meetup affiliations. Her full LinkedIn profile can be found here:
http://www.linkedin.com/in/meredithmonroe
(the profile used the same profile photo found on meetup.com)
In a way, it's like buying a very targeted email list.
However, I'm sure there will probably be a backlash in this case, and I doubt Meredith would show up at any of these events because she'll probably get stoned to death there.