Skype for Linux 1.4 doesn’t support sending SMS in the User Interface yet, but the functionality is supported in the core library used in this release, thus it is possible to send SMS using the Public API.
I have added to my Skype command-line tools a little application for sending SMS. Usage is simple, call it with the phone number and the message to send:
$ ./sk_send_sms.py PHONENUMBER Hello world
Of course you need Skype credit for this to work. The tool doesn’t implement validating your phone number. This allows recipients of your SMS to see your mobile number as the sender, instead of the first 11 characters from your Skype Name. This can be done with Skype for Windows.
Update 2007-08-30: About the Initialization failed errors that some got, they are probably because “sms_sender” is not authorized to connect to Skype. First time the script is launched, Skype asks if you want to authorize it to connect to Skype. Later the authorized applications can be seen in Options => Public API. I fixed the scripts to show better error messages in this case.
Update 2007-12-12: I rewrote the script to use the Skype4Py wrapper. Hopefully this should solve the issues people have been seeing. As a bonus it should now work under Windows and Mac too (didn’t test that).