I'm reading the Spartan 6 user guides, specifically the Memory Controller Block guide. I quote the introduction:
The Memory Controller Block (MCB) is a dedicated embedded block multi-port memory controller that greatly simplifies the task of interfacing Spartan-6 devices to the most popular memory standards. The MCB provides significantly higher performance, reduced power consumption, and faster development times than equivalent IP implementations.
I don't know what 'IP' stands for in "IP implementation". Both "intellectual property implementations" and "internet protocol implementations" don't make sense in this context.