Android Gallery Won't Display Updated Pictures

When I edit pictures from my Droid on my PC and add them back into the Gallery, the updated pictures do not show up, instead I get this icon of gray mountains backed by a film strip.

I can see the pictures in thumbnail view but the main picture view only shows the gray mountain icon.
It doesn't happen on every picture I edited, but it does on most of them.
 
The followng procedure definitely fixes the problem for me:

1. Connect droid to computer using USB cable. (This un-mounts the SD card).
2. Run the SDRescan app (From the Android Market, by Benjamin Rosseaux, suggested above.)  Note: Running the sdRescan app while the droid is hooked up to the computer via USB takes a little while to complete. Also, it doesn't make sense to run this app at this time because the SD card is un-mounted, but it does seem to work...
3. Disconnect droid from computer/USB cable. 
4. Open the Gallery.
5. It will take some time while the gallery is rescanned. 

Google needs to write a real gallery rescan program.
It seems like the gallery cache is not being updated very frequently.
Is there a straightforward way to clear the gallery cache?

(Droid X with OS 2.3 installed)