I've posted a couple of times about the gang at Up2Speed.com, which was formerly Adventive and MarketingFix.
Adventive ran business-related email discussion lists and still does under the Up2Speed name. Since being acquired, they've opened up a new email discussion list called I-Blog.
By subscribing to I-Blog I get an email digest twice a week with various discussions and information about how weblogs are being used by businesses. I've only seen a few so far, but I'm pretty impressed with the content. There don't seem to be may resources out there focusing on business blogs. Rick Bruner moderates with a good voice and keeps everything rolling and on target.
As part of this focus, Rick also keeps a growing list of businesses that are using weblogs on their corporate web sites.