If you find other types that aren' t supported, please report them as a bug (if not already reported) and provide as much information as available.
There are dozens of VARIANT types and combinations of them. Most of them are already supported but a few still have to be implemented. Arrays are not completely supported. Only single dimensional indexed only arrays can be passed between PHP and COM. If you find other types that aren't supported, please report them as a bug (if not already reported) and provide as much information as available.