STOCK Droid 2 Extended batt upgrade DOES fit the Droid 1 and IS functional. The door included with the battery fits without ANY modification, direct fit.
Theres probably a few threads floating around already but go buy one while they still have them in stock before this secret is out hah.
The biggest difference I notice is at work while my service is terrible... about a 20% difference or so in usage during the daytime.
Only adds about 1-2mm at most of thickness on the back side, cant even really tell. The color is still black but with a shade of blue sparkle it appears. You can only really tell in direct light. Even at that, still amazing.
Ide say a worthy purchase for anyone looking for a tad longer run between charges