Marcia - 9:03 am on Sep 4, 2007 (gmt 0) [edited by: Marcia at 9:04 am (utc) on Sep. 4, 2007]
Forget spam and forget SEO for just a minute: studies have shown that USERS have come to expect that the site logo graphic can be clicked on to get back to the homepage. If it's user friendly, common practice, user expected and good for usability, there's no need to abandon it. Just don't spam it up - be very moderate and keep the alt text to a bare minimum, just like if Matt Cutts were looking over your shoulder.
[edited by: Marcia at 9:04 am (utc) on Sep. 4, 2007]