Anyone Heard of Linktub?

I just heard about a new service where sites can sell links from their website to another. What makes this service seem interesting though is that they scrutinize both sites in terms of compatibility with regard to link profiles and content.

Has anyone heard of them?

no, it seems like a silly things to do.

… and I hear the approaching rumble of another Google algorithm update …

It seems Google have finally decided that links are more abused than used, and since Panda the weighting has gone down with penalties for those that obviously use artificial links in an attempt to bump their serp ranking. As Penguin followed this path, it stands to reason that the next update will target artificial links further. That makes paying much attention to links at best a waste of time.