Here is a rather skeptical view of the viability of blogging as a business from Graeme Thickins (via Dragos from @rgumente).  In summation, here are Graeme's 10 points of why he believes blogging and business are not a good match:

Here are a few issues I have: some businesses "do passion" all the time, in fact, passion is a key ingredient for success if you are a startup (well, in mathematical terms, a necessary but not sufficient condition).  As for gossiping, I would say that depends on the nature of the business ;-).  Even in the telecom industry, it is nice to read a few "insider" postings that one sometimes can get at Om Malik's blog, for instance.  So for blogs like B2Day (the Business 2.0 blog), a bit of gossip certainly cannot hurt.  As far as public experimentation, consider again a counter-example from the telco world (there are many, but carrier focus groups are one of them).  Businesses do not like to bare their souls?  Try telling that to Jonathan Schwartz, the Sun CEO (yes, he has his own blog).  Burning time?  Well, as long as employees work on their blogs during their own time, there should not be any problems (their free time is sacred and they should be at liberty to use it however they choose).  As far as advertisers, I have a couple of words to say: Google AdSense.

Graeme's points are well taken, despite the above notes - the case for blogging in business still needs to be made or to be better articulated.