Yesterday I finished Mathematicians in Love by Rudy Rucker,

This is a typical wild satiric ride from Rucker, starting off in an alternate version of Berkeley where some math PhD's figure out how to predict pretty much anything and ending up traveling through some wacky alternate dimensions created by jellyfish. And those are some of the more normal things that happen.

Overall, it's a fun book but the thinly veiled swipes at the Bush administration just seem weak and out of place.

I just finished The Ghost Brigades by John Scalzi, sequel to Old Man's War.

I thought Old Man's War was a good book, although it didn't add much to the classic military SF (Starship Troopers, Forever War) it seemed to emulate.

Ghost Brigades is better in that regard. The first book focused on the future's version of the infantry while this book focuses on the special forces, an elite group of soldiers created just for this purpose. It can also tell a more involved story, since it doesn't have to do as much as the first book to describe the background universe. This convoluted plot involves a human traitor that is working with a few other alien races against the human army.

It also avoids a lot of "sequelitis" problems - there are very few overlapping characters from the first book, so it tells a new story and advances the background story as well, rather than just repeating large pieces of the initial book.