To me, this is closely related to how widely do you disclose to your guild that you have a blog. If you're someone like Matt from World of Matticus, there's no way to get around it. You run the guild, and everyone knows about your blog. In fact, many of your members may have even joined because of it.
But Matt's case is an outlier I'd guess. Most of us folks who blog about WoW are not Internet famous. We're just folks who play WoW and love to write, and share screenshots or fiction or what have you with other like-minded folks via our blogs.
Some of my guildies know that I have a blog, as do all my Officer colleagues. Ditto for my twitter account. I don't have a link to my blog in my signature file, because I like to point to our raid logs instead, since that is something I want more folks to go peek at. I maintain my craftables lists on my blog, linked out to from our forums, and on a couple of occasions, other guildies have mentioned my blog and tossed out a link to it.
But it just doesn't feel right to promote my blog or specific blog posts in our forums. I feel that those who are interested in what I have to say will make their way here. Similarly, in answer to Anea, no, I don't think I'd include a link to my blog from my armory profile were that option available.
I would be concerned that were I to have a link to my blog in my armory, my SPAM comment load would increase. I would expect gold farm spammers to harvest those links and post malicious links more often. I'd also expect crazy comments from fail PUG members, or from declined guild applicants to be on the uptick for folks. Mostly though, I don't see that it would cause an increase in good conversation on the blog due to the reasons folks look you up in armory (from grouping with you or inspecting your gear) don't seem to usually match up with why folks make their way to my blog (because they are interested in raid topics or shadow priesting.)
All this said, I am hoping that the new Battlenet allows for creating a user profile, that you can control privacy levels on, so that you can share your contact information, including blog links, IM clients, twitter IDs, toon names across forums, etc.) with friends who you choose to grant that access to. I miss some of my Alliance buddies that I almost never get to see and would love to have an easy way to drop them a note or keep up with what they're doing. A facebook style update feed for those folks, that I could comment on, would rock!