No, this isn't anything mind-blowing. It's purely an appearance thing and is incredibly geeky. You may even know about this already, but it's worth sharing in case you don't.
So, here's the thing. Reeder 3.0 displays your account name in the bar at the top of the app. Considering that your account name is most likely your Gmail address, it's usually truncated, and looks all ugly up there:
Luckily, there is a setting to change what text is displayed up there. Just hit the "Settings" button in Reeder, then tap on your account, and then change the description to whatever text you want to read in the top bar:
I changed mine to simply say "Reeder", but you could change yours to "Google Reader", or whatever else you would so choose. Just so long as it isn't an ugly, half-of-an-email-address with an ellipsis. The result is looks much prettier:
I know. Super geeky, not useful at all, and totally unnecessary. And yet, so necessary at the same time…