Contrary to a lot of the questions here on meta, I'm not having trouble logging out, but rather staying logged in.
Before, sessions seemed to last "forever" but in the last few days I've found that every time I open a new tab for any Stack Exchange site, I've been logged out.
I'm on Google Chrome (Developer Build, currently version 26.0.1384.2, but updated very often), Mac OSX Mountain Lion.
Most notably, the problem has been with Stack Overflow as it's the one I use most often. Meta and Area 51 may have had the same problem, but because I use those sites less often, it's not too unusual to find myself logged out.
Is this some setting I've changed or has the login system had a recent revamp? Possibly something that's changed in Chrome with regard to storing session information?