I think link diversity is one of the most important aspects of link building.

The part about building links that are meant to be permanent is easier said than done, of course. Even when you manage to get quality links, there's no sure way of knowing which websites will be parked pages in 6 months.

I think the percent is high and don't think they disappear but do agree links/link pop passed fades over time as the algo changes.

I've made this one "hot" as I think a lot of people missed over the weekend.

It's a good article that provides info on links that many may not realize.

Hi My name is Bruce and I am new here but it is looking like a great place. On topic I agree that link value seems to deminish with time but the quality of the site or page rank of the site of the link you are posting on means a lot. I also agree it is best to stay diversified. I see a lot of people just trying to use one site like Ezine and it is powerful but if most of your links come from there is it still more powerful.

Link diversification and relevancy is must if you are doing link building.

Nice post!

Thanks Jill and everyone else for making this story hot.

I can confirm that it is much higher.  At http://linkrep.seofox.com we re-spider all the links that have been seen in the last 5 years for our clients.  I am seeing at least an 80% drop off rate.  I don't keep track of the time period but I do see a huge loss of links across the board.  We do comparison reports for sites that rank in the top 5 for very competitive keywords so I'm talking very high quality sites that are loseing links.