Here are a few things that seem to be new in PlanNine the OperatingSystem.
File Servers simplify operations on disparate objects to the basics: Open Close Read Write Create Delete. Even the windowing system, rio, serves a tree of files to simplify operations on windows: e.g. Read a window's size, grep something out of its text, Write its label...
this takes anonymous or authenticated FTP and grafts the remote tree of files onto your own name space
makes CDrom, CD-R, and CD-RW look like simple files and directories. It took me only a few minutes to figure out how to write a CD on my CD-R
makes the files on tape appear in your name space, so you can use standard tools like grep, wc, spell, etc.
the kernel serves your environment in what looks like files in /env -- e.g. cat /env/path returns the list ( . /bin )
(aka 9P or 9P2000) a message-oriented file system protocol; it simplifies the design of the file servers listed above. It is network aware, and allows importation of file trees of any sort from other hosts. For more info and implementations in many languages see http://9p.cat-v.org
IP Light. While TCP/IP are fully supported, IL has less overhead but is similar to TCP.
Unicode pervades every aspect of PlanNine. UTF-8 encoding makes transmission of ASCII streams transparent from process to process, including those on other platforms.