Broda is an important figure in the history of BF theory and Broda has just written an encyclopedia entry on BF which he posted today BF system—encyclopedic entry B. Broda http://arxiv.org/hep-th/0502045 [Broken] I dont know if this is good or not but it is short and I am going on Broda's reputation, and altho I'm not qualified to judge, it looks OK to me He give four references, one of which is to a John Baez lecture notes published in 2000. Near the end Broda says "One of the most exciting applications of BF systems is gravity . 3D gravity is directly identified with a BF system, and the cosmological term plays the role of the cosmological term in gravity. 4D BF system can be a starting point for a novel formulation of 4D gravity (direction pioneered by Plebanski). " his reference  is to the Baez lecture notes.