After circumnavigating the EMP/SFM building we finally found where we were supposed to be. This happens to me pretty much every time I visit - I always choose the entrance that is the farthest away from where I'm actually going, it seems. But we knew we'd found the right place when we saw Duane from the University of Washington bookstore's Science Fiction department holding court amid a huge spread of books. Even better, we found nihilistech. I resisted buying any (more) books and we went in and ensconced ourselves in the auditorium.
Stross is a delightful reader and entertaining character. His t-shirt said I make stuff up. As far as Halting State goes, it's more like he extrapolates really well. (I hope he's making the Atrocity Archives up, though. Fervently.) He read from Halting State, and now I have to get ahold of a copy to find out how it all ends up - but I was approaching my limits wrt peopleness, so instead of elbowing my way thru the crowd to get a copy from the table on the way out, I/we merely headed home.
FYI: The UW bookstore is also co-sponsoring appearances by Laurel K. Hamilton on November 1st (at the U District store) and Clive Barker on November 5th (at EMP/SFM).