Lena and I just went out of town for a long weekend, and I took along
Axis by Robert Charles Wilson, the sequel to his fantastic novel
Spin.
It's a sequel in the sense that it follows up on some of the world-changing events and the non-human entities revealed in the first novel, but
Axis is by no means a direct follow-up to where
Spin left off, in terms of time, location, or characters. One of the major characters of
Spin is a fairly minor character here, and much older, but for the most part this is a whole new group of people in new circumstances, several decades after the end of the last book.

I don't think I'd recommend this book to people who had not read
Spin, so I won't bother explaining about the Hypotheticals, or the planet connected to earth via the arch in the ocean -- if you read
Spin you'll know what that's about, and if you haven't read
Spin then you shouldn't read Axis yet! But basically, this is a story about human beings finding their horizons expanded by a non-human race (or non-living collective entity, maybe) and spreading out to explore a second, connected (but not nearby) planet.
Overall I enjoyed this and I'd rate it as maybe a B- or B grade, which would be fine if it weren't for the high expectations I had following
Spin, which was certainly A or A+ material. I'll certainly be in line for the next sequel which I believe is coming in 2010 or 2011.