A WebmasterWorld thread asks how long does a link pass link juice after the link was removed from the web page? For example, a web page has a link to your page and then that link is either removed or the page or site goes down, how long will the search engine consider that link a vote of confidence for your page?
I think the obvious answer is as soon as the search crawler notices the link is gone, communicates that to the index and the index updates to correct the link popularity factors for that page. Not every search engine is quick to do that. I know that in the past, Yahoo was incredibly slow to devalue links that were dropped. Google is typically faster.
What do you think?
Forum discussion at WebmasterWorld.