Django-resolvetime is a Django filter to convert a python datetime object into a format that specifies the time difference between the time of the datetime and now. I developed this for a personal project of mine and decided to opensource since I could not find a filter available to get the job done.
The code is hosted at http://code.google.com/p/django-resolvetime/. Installation and usage of the filter is straight forward. Instructions are given in the README file.