Minidetector is a simple middleware and associated decorator that will add a “.mobile” attribute to your request objects, which, if True, means the requester is coming to you from a mobile phone (cellphone), PDA, or other device that should be considered small screened, or have an underpowered browser, such as games consoles.

This mostly works using a list of search strings, though there are a couple of other tricks, like detecting the presence of Opera Mini. The strings are in an easily-parseable text file, and thus can be used for other similar projects.