All, Here's an anecdotal example of a forum split:
When I was a full time online bookseller (from 2002-2004) eBay's community forums were a great resource in the begining. There were about 30 different forums, 2 of which I frequented, "booksellers" and "packaging and shippping" as those were the 2 that applied to my business.
Now, there are approxiamtly 100 different forums
http://pages.ebay.com/community/boards/index.html
If were still in the business and wanted to keep up on discussions in my field, I'd have to frequent:
-Booksellers
-Packaging & Shippi ng
-Half.com
-Seller Central
-Part Time eBay Sellers
-Building an eBay business.
In addition, the off topic forum, has been split into around 6 random forums.
I am getting back into the business somewhat now, and I am overwhelmed by trying to poke through 6+ different forums rather than just 2 to find the information I need. I have given up on the community boards there, and many other big eBayers I know have done the same.
I realize that this is just one isolated story, but I felt it could serve as an example.