There has been some recent buzz about Google changing how they hande the NoFollow attribute, and how it’s the end of the world. SEOs are running around in circles, and there’s talk of moving to JavaScript and iframe commenting systems so Google can’t read them.
First of all, slow down. Google can read iframes and JavaScript. Google very likely is already programmatically diferentiating between comments and page content anyway, and tweaking their rankings accordingly. PageRank is not a cut-and-dry “links in minus links out equals rank.” It’s a complex system involving a lot of calculations on Google’s part. I imagine they value links differently depending on what sort of link it is.
Second, stop worrying about it. Google’s business is to provide good results. If everyone tries to cheat the system with a bunch of silly schemes (such as PageRank sculpting and JavaScript links) Google will just change things again. If everyone plays by the rules, and doesn’t worry about their ranking too much, it all works out in the end.