BTSMS allows you to send SMSes from your PC using any bluetooth enabled mobile phone. It makes use of the Dial-up Netwroking Profile provided by the bluetooth handsets. You can directly get hold of the dource tarball from here.

Alternatively source can be checkedout from the cvs as follows:
cvs -d:pserver:anonymous@bt-tools.cvs.sourceforge.net:/cvsroot/bt-tools login
cvs -z3 -d:pserver:anonymous@bt-tools.cvs.sourceforge.net:/cvsroot/bt-tools co -P btsms