mongodb/mongo-ruby-driver — pull request #65 by omikronn (2011-10-13 23:04:28+00:00)
Title: Raised the maximum limit for individual documents to 16Mb

Because you promised :)

"MongoDB limits the data size of individual BSON objects/documents. At the time of this writing the limit is 16MB."- http://www.mongodb.org/display/DOCS/Documents