It's a little amusing to observe Twitter being used as a sort of "transport layer" for services because of how easy it is for people to use it; a few decades ago, to interact with a service you would probably open a TCP connection to it and communicate in a service-specific protocol. Later, that was largely replaced by the ubiquitous HTTP "web API", and now we see services built on services like Twitter which are already using a HTTP-based API.

Earlier, someone tried doing similar things with another calculator: http://www.hilarymason.com/blog/a-quick-twitter-bot-bc_l/