20 Gbps transfer speeds aren't expected to hit Thunderbolt until 2014.
Back in February 2011, Intel's Thunderbolt interface finally hit the market in Apple's MacBook Pro, using the same connector as the Mini DisplayPort. Combining PCI Express and DisplayPort into one serial data interface, it offered data rates up to 10 Gbps and the ability to "chain" supporting peripherals.
The technology, co-developed by Intel and Apple as a replacement for USB and other connections, just recently arrived in the PC sector with a 2nd-gen "Cactus Ridge" chip. However it's mainly offered in high-end desktops and notebooks most likely due to its price: $20 to $25 per Thunderbolt chip. But as with all new emerging technology, Thunderbolt will become more mainstream as the price comes down.
However already there's talk about a 3rd-generation "Redwood Ridge" chip, but whether its pricetag will be lower remains to be seen. The chip is supposedly slated for a 2Q13 release, launching alongside Intel's Haswell "Shark Bay" processors. It will support 10 Gbps data rates, DisplayPort v1.1a and DisplayPort v1.2 Redriver.
That said, any hopes for faster speeds across the Thunderbolt interface won't be realized until 2014. Intel is expected to release a 4th-generation Thunderbolt chip codenamed "Falcon Ridge" sometime during that year, providing data rates up to 20 Gbps through two channels. This should make the interconnect even better for daisy-chaining multiple high-speed devices like monitors, high-quality audio and video interfaces, and RAID arrays.
Back in May, the first Thunderbolt-compatible motherboards entered the PC market including the Asus P8Z77-V Premium, the MSI Z77A-GD80 and the Intel DZ77RE-75K. Unnamed sources said that Thunderbolt would become one of the key specifications that motherboard makers will be competing with in the second half of 2012. Yet due to the current price of Thunderbolt chips, non-Intel chipmakers won't be able to make a profit from the technology, as most can only develop products such as Thunderbolt adapter chips.