You can send SMSes from GNU Emacs on the Nokia N900 GNU mobile phone.

The following approach uses the diamondcard.us SIP service, for a fraction of an SMS cost, if you have an internet connection.

To send SMSes from GNU Emacs:
http://sumoudou.org/0/18.html

If you use BBDB in GNU Emacs, you can use a great frontend interfacing with BBDB, which has oneclick SMS sending, automatic recordkeeping etc.:
http://sumoudou.org/0/19.html

The above package also enables SIP oneclick calling from GNU Emacs with recordkeeping. I'll be putting together instructions for this later and will post them.