The latest update came down to enable flash support and now Droid owners with custom ROMs are once again dealing with the annoying system update message. The way to end this annoyance and prevent the FRG22D OTA update is fairly straightforward.
Start up Root Explorer or Astro and navigate to /system/build.prop
Open this file in a text editor and replace this line:
With this line:
Save the file and reboot your Droid. You will no longer get the OTA update notifications because Verizon will believe you already have it.