The new MacBook Pros, along with all of their other speedy goodness, have SATA3 interface for storage access (but not to the optical drive). Apple’s build to order solid state drives are SATA II and are very speedy.
However, Macotakara popped in a Micron RealSSD SATA III drive and got some pretty incredible speeds. In fact, it benchmarked at about double Apple’s BTO option(!!) on read speed (450MB/sec) and 50% faster writes (260MB/sec). That means it takes just over 2 seconds to read a Gigabyte and under 4 seconds to write one. That is fast.
See SATA3 vs. SATA2 BTO vs. HDD below: