Some other drum programmes have a feature like this, preset patterns that can be pulled into the timeline. It would be a really quick and simple way to arrange a song.
The idea would be to have a pattern bucket that you could drag from into the pattern editor (think dragging audio files from the region list in ardour onto the timeline and being able to easily arrange/duplicate them). It could be arranged by beats, fills, etc. I don't know how easy or hard this would be to implement (i'm assuming not easy :P) but it is something i have often thought would make a great piece of software even better.
You could save patterns as you go along and before you know it, you would have a huge bucket of presets that could aid you in quickly putting together a drum track to that song you just came up with on the guitar :)
Has there been any consideration given to such a feature?