Do the new macbook pro models (2011) still have a 4 partition limit?
This is not a limitation of the hardware. This is a limitation of the MBR partitioning scheme required to allow Windows to boot with other non-Windows operating systems. The MBR partitioning scheme only supports 4 primary partitions.

The GUID partitioning scheme that Mac OS X uses by default is able to handle more that 4 partitions but not all operating systems support GPT.