Works for me.

There is a download region option which allows to download maps possibly for offline using.

Here a guy bundles an iso with full bluemarble data. I am looking something similar to this --full OpenStreetMaps bundle or Satellite view imagery.

http://www.cornelius-schumacher.de/marbleinabox.html

For offline routing monav is used which also downloads seperate routing files --wish there was a way to download the Conus pack at one click instead of fetching states separately.

Any idea, where these maps are cached on disk?

Thanks for the simple/clear instructions at http://userbase.kde.org/Marble/Maemo/Installation and for the offline use.