I just finished
Stone by Adam Roberts, which was kind of interesting.
I don't think I'd read it again, which isn't much of a recommendation, since I've got some books which I've read multiple times, but it did have some interesting snippets.
One element I found slightly irritating is that the author has obviously got some information about Quantum Physics and the collapsing of wave-functions, but doesn't really understand what observation means in this context, and takes a rather metaphysical approach to it, which isn't really what Quantum Physics says.
(Don't click the link to Wikipedia if you want to read the book, it isn't actually a very accurate synopsis, and is full of spoilers which give away the entire story).
Now I need something else to read on the Tube/Tram home!