http://wiki.linuxquestions.org/wiki/SATA

Serial ATA, also known as SATA or S-ATA, is a bus used to communicate between the CPU and internal storage devices such as hard drives and optical drives. It is designed to eventually replace the ATA (also known as IDE) bus. Traditional ATA is beginning to be referred to as Parrellel ATA, P-ATA, or PATA to avoid confusion.

The main difference between SATA and PATA is in the cabling. SATA does away with the master/slave relationship of PATA (hence the difference in names), as well as PATA's ungainly ribbon cables. Instead, SATA has much slimmer and easier to manage cables, which will enable better airflow through cases. The connectors are keyed, preventing connectors from being plugged upside down. Truly native SATA drives will have different power connectors also.

A third advantage of SATA is hotplugging.

Currently, SATA has a transfer rate of 150 MB/s, which is only 17 MB/s more than standard PATA. However, with the introduction of SATA II, this is expected to go up to 300 MB/s, with 600 MB/s being released sometime around 2007. The faster bus isn't expected to affect performance in the short term, since hard drive performance is usually bottlenecked by the moving parts of the drive.

During the transitional period before true native SATA drives are released, most SATA drives actually have onboard PATA controllers, which connect to SATA by a bridge. This generally causes a 30-50% performance drop. Also, PATA power connectors are still being used.