One of the things that's really impressed me about 10gen is how much effort they've put in to running and promoting MongoDB events. We've been collecting them on Lanyrd and they've been involved with 17 in the past 12 months, and have another 8 coming up:

http://lanyrd.com/topics/mongodb/

They wouldn't be spending all that time and money on events if they didn't work, so I'm beginning to think this is a major factor in the huge amount of buzz surrounding MongoDB compared to other NoSQL alternatives.