Yeas, there is a small "note" there. But for me the problem is not that the author didn't know about 2GB data limit.

The problem is that Mongodb didn't complain when he was inserting data above the limit. A data store doesn't complain when it runs out of space? It should be mentioned as the biggest problem with 32bit version.

Looks pretty obvious to me; however I am a novice when it comes to RTFM..