I noticed that according to Quantcast your uniques is flat for the last four months or so (about 15m per month roughly). The flatline is pretty dramatic on a three year scale. Is there an expectation that growth will pick up?
Stack Overflow always experiences a "summer lull", typically starting around March or April.
Our best guess is lots of people taking vacations offsetting growth, on the 3 year graph you'll notice growth resumes sometime around September every year.
I honestly don't care* too much about it, we're in the business of quality questions and answers; traffic is a side effect, not a goal.
(Disclaimer, SE Inc. Employee etc. etc.)
*Provided it's high enough to pay the bills naturally, which isn't that hard to do.