Cheap deals, great games, and a stable, easy-to-use environment are just a few of the reasons why Valve's online game distributor Steam is so popular. That and it's a great place to interact and play with other gamers, which is why it recently broke records with over 6 million active users logged in at the same time.
But one thing that Steam users weren't so crazy about was the inability to install games in more than one directory and partition. If you ran out of space, you either had to uninstall some of your games or move the entire game library to another drive.
With it's newest update, Steam now finally allows users to pick any drive on their computer to save their games on. In order to do this, you'll have to create an alternative folder to where you'll be saving the games. After clicking on download for any game, you should see this window.
The new "Chose drive to install to:" will give several drive options to save your games on. If you haven't already created a new library, you'll have the choice to do it from Steam.
Note that you'll only see the option to save to alternative drive or partition if there are more than one currently connected or active on your computer. So, if you only see one drive to select, more than likely that's all you got.
Thanks to Martin Brinkmann over at Ghacks for pointing this out.