Importance:
Medium
GG says to use absolute links, just in case.
GoogleGuy Says: [
Link to quote]
Personally, I lean toward always using absolute links. I think we've always gotten this right, but not every new spider will. My philosophy is KISFBTCATOTBD (Keep It Simple For Bots That Could Always Turn Out To Be Dumb). Another way to say it is that the more help you give spiders, the less chance there is that a spider/bot will mess it up.
So even though we should handle this correctly, I lean toward using absolute links just to be safe.