How does RSS to SMS work?

here is a link to the Lifehacker article about Pingie, an app that scans RSS feeds and converts them to SMS.

Generally, from the internet sending an SMS out is free for the sender- thats how twitter can update to your phone and not break the bank. True, it ups the client’s SMS costs, but that’s usually a non-issue.

You could also use something like Twitterfeed to send the rss to a Twitte. Account and the subscribe to that Twitter account with a separate account. The only benefit of this approarch is that you have another content access point if you need it.