Today I updated a project I'm working on from rails 2.2.something to 2.3.3. Then, I started getting the following wacky error.
undefined method `rewind' for #<TCPSocket:0x3631e58>
Turns out if you see this after a rails 2.3.3 update, you might just need a phusion passenger update (I was on passenger 2.1.3, apparently this error happens on passenger 2.1.2 too)
sudo gem update passenger
sudo passenger-install-apache2-module
Put the lines recommended by the install script in your apache config file, restart apache and you're good to go.
Hope this helps someone.