The idea of joint blogging in a niche topic area is not new. But consider this: sites that specialize in an area of interest and have several contributing bloggers who are experts in that area seem to be doing very well. Om Malik has come up with the name Micro-pubs for these types of blogs that are actually more like publications. Malik described a Micro-pub as "a combination of old fashioned newsletter, blog and a directory service, managed by one to 10 people."
JiWire, which is a guide to WiFi spots, was cited as an example of what Malik is talking about. Anyone seriously into blogging about some specialty should seriously consider morphing into a Micro-pub.