If you want to connect your eSATA drive up to your PC via a USB 3.0 port then this cable will do this for you.
The cable is called the SIIG USB 3.0 to eSATA adapter and allows eSATA drives to connect up to a USB 3.0 port on your computer to transfer data at up to speed of 3GB/s.
To get it working you'll need to have your own eSATA cable to hook up your drive, but from what we understand there is enough power provided by the USB 3.0 port to keep your eSATA drive powered meaning no external power source will be needed.
The USB 3.0 to eSATA adapter is capable of reading and writing drives up to 2TB in capacity. Also, drives can be hot-swapped meaning you do not need to switch power off before removing the drives. Just go careful when doing that though and don't move the drive too quickly while the platters are still spinning to prevent damage from happening.
As well as being a USB 3.0 connector, the adapter is also backwards compatible with USB 2.0 allowing you to take the adapter around to other PC's that have older/slower ports and still access your data.
The adapter works on Windows based machines running Windows XP, Windows Vista and Windows 7 as well as Server 2008. However, no drivers for Apple or Linux based machines are available at the moment.
The adapter costs $49.99 and is available now. Full details of the device can be found over on the SIIG website.