VS 2010 has a new “start page” that displays by default each time you launch a new instance of Visual Studio.  In addition to displaying learning and help resources, it also includes a “Recent Projects” section that you can use to quickly load previous projects that you have recently worked on:

The “Recent Projects” section of the start page also supports the concept of “pinning” a link to projects you want to always keep in the list – regardless of how recently they’ve been accessed.

To “pin” a project to the list you simply select the “pin” icon that appears when you hover over an item within the list:

Once you've pinned a project to the start page list it will always show up in it (at least until you "unpin" it).