The four patents in question cover "obvious" features used by countless sites today. They mostly describe ways to present related information to consumers while they browse the Web. For instance, one patent allows a site to offer suggestions for items related to what a person is currently viewing. Another allows readers of an article to locate related posts.
Those are pretty broad descriptions, so there's no telling how successful the suit will be. Most of the defendants haven't responded, but a Google spokesperson has said the suit "reflects an unfortunate trend of people trying to compete in the courtroom instead of the marketplace." You can read the patents in full here: 6,263,507, 6,034,652, 6,788,314, 6,757,682.