With just a few lines of code, Zeep Mobile's API lets your web app communicate with your users over SMS. Zeep Mobile makes it easy to:

Manage your users' mobile content subscriptions Send and receive SMS content These libraries take care of the HTTP Header signing and posting to the HTTP endpoint.

Currently there is support for Ruby and Python.

If anyone would like to contribute a client for their favorite language be it Java, PHP or assembler please drop me a line.
You will need an account in order to send messages. It's FREE as in beer. Head over to http://zeepmobile.com to create your developer account.