The aPE is a patcher program that can be used to patch packed/protected executable files. This is done by code insertion in packer/protector code so that the program can be patched normaly without the unpacking of the packed file. This means that you can now make smaller patches for packed executables. There is no more need for distribution of larger unpacked files... The aPE can patch tham while they are still packed!
:: Which packers are supported?
The complete list of the supported packers and their options can be found here. Curently there are 56 supported packers, and every packer has it`s own patching procedure. There is also a generic inline patching method that can patch many packers/crypters/protectors.