I went with a micro-blog, instead of a full out blog. Here is my twitter page:
www.twitter.com/florist
www.twitter.com
www.friendfeed.com
www.seesmic.com (if you want to do micro video blogs)
Most people, and I have seen research on this, do not want to read some long post, the cool thing about micro blogs, is you have 140 characters and people don't mind reading. I think that google likes the twitter feed on my page
www.chicfloral.com (I know it is ugly) so as for SEO, I am not sure. BUT having an interactive micro blog, so people can follow you, is nice when you want to hit your target market.
If you do go with a micro blog, DL this:
http://www.twhirl.org/ it makes it easier.
I crowd sourced, a few months ago, through my tweet, looking for a rose bush that produced green roses. Who ever got back to me first, they got a free Pralus ($8) bar of chocolate. A lady found a nursery back east, saved me 1 hour of time, she came in to get the chocolate. And it's not about her getting the chocolate, but she didn't even know I got hr hooked and into my shop, which she had never been in. Crowd sourcing is so awesome, and this is a way florists can use it and make new customers.
If you want to make your own blog site, like Heather did, use wordpress, she introduced me to them and they are the best.