We recently purchased two Promethean boards through a grant at our school. I chose the Promethean boards over the Smartboard because Promethean markets itself as being created for education. I like the resources that Promethean has available online. You can even search for resources by state standard.
I got an e-mail today about the Promethean Users conference coming up in April. Registration is free for the first 100 participants. (Registration opened up in March.) I probably can't make it this year, but I won't to keep in mind for next year.
There was a link to some videos on how to use the Promethean Board that looked really good. When I get back to work, I'll try to look at these.