Same poop, different gut - this one deals mostly with fecal transplants to treat bacterial infections
The gut flora as a forgotten organ - mostly dealing with diseases though touts the promise of obesity relationship
The environment within: how gut microbiota may influence metabolism and body composition - An excellent review of the current understanding of the role of gut flora in inflammation, disease, obesity, etc. The lead author is the researcher who did the fecal transplant study on obese men that demonstrated improvements in insulin sensitivity (see next link). I recommend reading this one. IMO, at this point, finding a bacterial solution to obesity seems to be a long-shot and lots of wishful thinking.
Fecal Transplant Flushes Insulin Resistance I really look forward to their upcoming publication of this work. It will be interesting to see the magnitude of the improvements, if it persisted past 6 weeks (e.g. was there a change in the IR as triglycerides returned to "normal"?), and the long term analysis of the microflora pre & post-transplant.
I wonder how much of this has less to do with the bacteria and more to do with flushing the gut. We recycle proteins and lipids in our intestines, and perhaps removing cholesterol and other phospholipids tricks the body into thinking it's in a totally different state of nutrition? If this is so, one would expect things to return basically to "normal" down the line.