I thought this was an easy to understand post that comparesBusiness Blogs to Email Newsletters.
I think the Wayne Hulbert makes good points, but I also think that weblogs are not a replacement for email newsletters. This is because of the way that email newsletters push information to inboxes. The expectation is different for the reader (something coming to me vs. me having to go to something).
To truly compare weblogs to email newsletters, you'd need to consider the role of RSS in pushing weblog posts out to subscribers. Much like someone would subscribe by email, people in the future will subscribe via RSS.
In my mind this is because people are lazy. OK, maybe not lazy- but many will not be proactive in seeking out information- but if it comes to them, it's more useful.
In looking at the push abilities of RSS, I do believe that weblogs can be seen as a replacement for email newsletters.
Oh, and... Happy Valentine's Day!