Here is version 1.5 of the PPC Altivec Plugin for IDA v5.6 which adds support for special instructions that are used by some PPC based devices. This was originally written by Dean Ashton and then updated by Takires.
This is useful when disassembling Xbox360 and PS3 binaries in IDA as they utilise these special instructions that are not supported by IDAs built in PPC disassembler module.
I have done some fixes to instructions that were previously handled incorrectly, as well as adding support for some new instructions. I also fixed an issue where instruction sizes were being reported incorrectly resulting in an incorrect disassembly.