For quite some time (some of the Seattle WETNET gang will say 'forever') I've been working on adding AX.25 support to embedded devices like your typical home router. Originally using the software from the OpenEmbedded project but eventually settling on OpenWrt and it's companion web interface X-Wrt.
The OpenWrt/X-Wrt AX.25 Project allows any router supported by OpenWrt to use the amateur radio AX.25 protocol. The core AX.25 tools and applications turn your router (along with a tnc and radio) into a TCP/IP capable packet system, a version of Digi_Ned makes it a smart digipeater while aprsd gives it the ability to be an APRS Internet gateway (igate).
All of it configurable through a handy web interface.
Currently I've been testing using the Linksys WRTSL54G and the Linksys NSLU2 both with USB to serial adapters.
Routers like the WRT54G can also be used with appropriate hardware modifications to provide serial ports. My SKAGIT digipeater/igate has been running with this code base for over 6 months on a WRTSL54G.
Gory historical details, instructions and links to pre-built beta images are here
Comments, questions and Discussion take place on the seatcp mailing list or I can be reached via XMPP/Jabber at JID: n7ipb at jabber.wetnet.net