Paul Stamets, a well respected mycologist touched on kombucha in an interesting article a little while back: http://www.fungi.com/info/articles/blob.html
I am getting so tired of people getting "so tired of the "unusual ingredients" trend (fad?) that some breweries seem to be embracing." I'm really not sure why one would get upset about this. Do you really think chocolate, coffee, new hops, grain styles, oak/woods and news yeast/bacterias are bad?
I love trying out new ideas in brewing. Some are good, some bad and some terrible but they are all interesting and make me think differently about everything I consume and the endless possibilities to make something that challenges my palate. This is part of what takes brewing from craft into art. Brewing, being pushed by homebrewing and the internet, is really moving into it's golden age in the US.
I think a kombucha culture addition could add a lot of interesting brett and acedic acid baceria flavor contributions to a beer. I am not sure how easy it would to balance those as kombucha is supposed to have a certain existing natural symbiotic balance that I would think the alcohol and pH change from regular yeast alter up but I would think a blend could certainly be interesting. My sister who brews a bunch of kombucha recently tried a little bit of my NB La Folie and said it reminded her very much of kombucha grown under certain conditions.
This guy: http://www.themadfermentationist.com/
has brewed a couple beers with kombucha culture with some interesting results.