I wrote a free application (which now runs only on Windows but will soon run on OS X and Linux too) that allows you to send MIDI data over an Ethernet / LAN connection.
Basically if you are using multiple PCs/Laptops and want to drive them from a single PC this tools allows you to get rid of MIDI interfaces (between PCs) since it can send the MIDI data in real time over the LAN.
An ethernet based LAN is much faster than a physical MIDI connection and can potentially forward an unlimited number of MIDI ports / channels between hosts without the need of point to point connections because the LAN uses a star topology (PCs connect to the switch).
Since everything will be open source, including the protocol it could easily get integrated in keyboards that provide a LAN port, especially PC based keyboards since they are fully programmable.
You can get EthernetMIDI here: http://www.linuxsampler.org/ethernetmidi/
see here for additional comments and infos. http://www.northernsounds.com/forum/showthread.php?t=36461