Yeah, if you liked diaspora then permutation city will have you picking your jaw up off the floor in a similar manner. Schild's Ladder is the third in the unofficial trilogy (he denies any connection, but I definitely reckon they form a nice trio) and it's pretty hardcore: lots of quantum mechanics and graph theory actually driving the plot.
A fascinating thing about diaspora: if you read reviews of it, opinion is split between those who see it as a story about nerd-heaven, which to me is how egan wrote it, and those who see it as a dystopia, basically a vision of hell. Apparently to a lot of people, the book reads like pitch-dark satire. I'm guessing there aren't so many of those people here.
EDIT: Bonus scott aaronson quantum conciousness essays! Wooooo! Egan fans will like these:
http://arxiv.org/abs/1306.0159
http://www.scottaaronson.com/blog/?p=1951