Then there's the Walnut St. complex in Shadyside, a little further away (harder to walk), including the usual upscale stores (Apple, etc.) and some decent coffee shops with Wifi.
Much further east on Forbes from CMU (probably easy bus access), there's the Squirrel Hill complex, with a lot of options on Forbes and on Murray.
Hope that helps a bit--I'm not really a local, but I do get in there fairly often.
Your Inner Vagabond in Lawrenceville is absolutely sublime but it's a little too far to walk. It's worth the short drive/bus though. I have never seen a better drink menu in a coffeeshop. http://www.yourinnervagabond.com/
If you are a l337 hacker you can probably get yourself on the CMU wifi.
And if you'd like to meet for coffee or food one evening, maybe we could throw together a mini HN meetup. We have one tentatively planned for the 28th.