Android Gallery Problem

Every Android phone I've seen so far has a problem that all of a sudden recent photos are missing from the Gallery.
Most users then think the picture they just took has not been saved to the phone or sd-card.

Wrong.

This is - as a simple google search will reveal - a problem of the media scanner.
The standard Gallery app relies on the MediaScanner to collect images from the various folders of the SD card. And apps should notify the MediaScanner when they store a new image/video/... on the SD card.

However, something is broken in the media scanner and it seems to die frequently - or at least not work.

Easiest work around (apart from rebooting the device):

Go to Settings and unmount and re-mount the SD-card.
This will force the media to be re-scanned.
However, this is a bad idea to do when you are listening to podcasts at the same time (because they are on the SD-card as well, which you are about to unmount...)

Therefore - even better, download an app like "Rescan Media" from the market place. All it does, is re-invoke the Media Scanner.
Just click on it - voila, the images will be back again.