I'm new to the OS developing scene, and opened my first OS project a month ago.
The current build of my OS is 30, compiled on 8/13/2010, and includes the following features:
FAT12/16 File System support
Dir command
Search engine
Text Editor
Full memory manager supporting up to 4 GB of RAM
Screenshot:
You can visit my OS project page (HeinanOS) at: http://heinanos.codeplex.com, there you can also download a preview build.