I would agree with that list, but in this order:
Inktomi Google Alta Infoseek. Yes, ink ahead of google. Ink is way out front on linkage right now - they have a killer, tough to crack algo - I'm still trying to figure the last tiny bit of the puzzle.
Some have suggested it is context sensitivity - no it isn't - Ink is NOT using link sensitivity in any way shape or form (period).
They ARE using link numbers per page (less than 75) and they have a killer algo to detect links pages (resources, bookmarks, links programs, etc). Links pages are not sticking in INK right now - no matter the source. I've about got it figured out.
Google is certainly using link context.
If it isn't in a sentence - good bye link.
If it isn't in a paragraph - good by link.
Graphic based links? for the most part - good bye link.
If there are more than 100 links on the page - good bye link
If it is a link to a site not in the Google db - the link goes on the list, but doesn't get credited until it shows up in the db.
There are 3 levels of link boost. Small, mid and large. The dividing line moves with an algo change. Small is around 10-50 links, over 100 is the first small boost, then somewhere around 500'ish and the last big boost is around 1000. Anything over that and it really doesn't matter.
Alta - pure numbers game. I'd guess about 10-15% of the algo is linkage. They use it more to trigger a spidering on a site from what I can deduce. Feedback rolled in a couple of weeks ago from BL members that alta was very active on their sites - that was just after around of submission started to stick in the db. I'm sure it was because thier link numbers were on the rise.
Inkfoseek - only heaven knows what Iseek is up to.