I have just uploaded the first public version of a new library that supports HopeRF HM-TR 433MHz serial transceivers and other similar 'transparent' transceivers.
The HM-TR is nice, inexpensive transceiver with a serial TTL interface. It is easy to connect electrically to Arduino serial ports, but does not have error detection or correction.
The HopeRF library provides classes for addressed and unaddressed, reliable and unreliable datagrams between nodes. 8 bit addresses, broadcasts, acknowledgement and retransmissions are all supported. Use it to build wirelessly connected networks and meshes of Arduino.
The code compiles on Linux and with only a little work could be made to run on Linux, interfacing to an RS232 capable transceiver via a serial port.
Documentation, download instructions etc are at http://www.open.com.au/mikem/arduino/HopeRF/HopeRF.pdf
Please feel free to try it and provide feedback direct to me.