I experienced something similar to what sixwheeledbeast experienced - crash while logging a track using modRana. A while after starting this a system hang occured. After some time I unlocked the phone I saw a lockscreen with the time shown as half an hour ago.

Btw. do you have any progress on the mapnik maps? It's something I'm really anticipating and modRana is absolutely useless if you go abroad or to some place with poor signal (or without signal at all)