This mod quite simply automatically switches to Fullscreen when Minecraft is loaded.
Simply place the downloaded file into the mods folder, start Minecraft, and enjoy!
Due to the simplicity of the mod and that the method did not change between versions, the 1.3.2 version is compatible with 1.4.2 and 1.4.4 as well! Unfortunately, it doesn't really matter since that's now an option in Video Settings.
Redistribution permissions: This mod may be redistributed by anyone and may be included in any modpack with the exception of Technic without prior written permission (which shall include a public apology to all of the mod authors whom they have blatantly ignored the permissions of)