Okay, it seems to be a failur alert. After 2 days now I restarted my n900 and without changing somthing now there are 50 MB of free space in rootfs available.

So it seems to be an other problem than only applications hungry for / - Memory.

If I remeber correctly I was sharing a 100 MB video file (I was uploading it) via flickr. Than the internet connection was gone and the next I remeber was that there was left no space. maybe this could be a possible reason?

I will keep my eyes open and fill a bug report if I am able to reproduce the memory loosing in a good way.

Thanks for your hints and descriptions!

Ciao jukey