Every single SE site (at least, the ones I'm a member on) have their "about me" sections (the box on the right side of your profile's personal info section) at 445 pixel width except for Gaming.SE and Progammers (which have it at 433 and 430 pixels, respectively).
If you want to see for yourself, take a look at my Stack Overflow profile and then my Gaming.SE profile and my Programmers profile. Those are all images, and altogether they add up to 445 pixels (I did it so that it fit perfectly). I neglected the difference in width between the three sites (and perhaps more).
So, why're they smaller on those sites? I'd like to think that the primary design aspects of each SE site are consistent throughout the network.
I would appreciate the widths of the about me sections of all SE sites to be equal.
EDIT: This is also the case with the network profile (the about section there is 380 pixels wide, which is incredibly small considering the amount of whitespace on the new network site).