Robert Scoble has posted confirmation that Google will introduce a new link attribute. OK, then I'll confirm it as well -- I've been told the same by my contacts at Google. Since official confirmation has now been leaked out, I see no need to hold back.
As Robert notes, the information is supposed to come out later today on the Google Blog. What will be the new attribute? Well, I could say "wait and see," but Dave Winer already leaked that part out. He didn't say it came from Google (it did), but he provided enough clues and follow up confirmations for people to know this is the nofollow attribute that will be introduced.
Exactly how Google will interact with the nofollow attribute remains to be seen. I'll be posting a follow up with those details. For background on it, see my Google To Add "Nofollow" Tagging Of Links To Fight Spam? post.
Postscript: Support has now been officially announced. See the Google, Yahoo, MSN Unite On Support For Nofollow Attribute For Links post for more.