What is it?
Light Peak is an extremely fast data transfer technology developed by Intel. It's used by your computer, and potentially other electronics, to interact with peripherals like portable drives and displays-- much in the same way that USB is used today. Unlike USB, though, Light Peak is based on optical technology, which means it transfers data as light instead of electricity. Aside from giving the technology its name, light allows for transfer speeds much faster than those reachable by even the latest iterations of USB and FireWire. Light Peak cables can move data at up to 10 GB/s, and are scalable to reach 100 GB/s in the future. Intel says that means sending full-length Blu-Ray movies in less than 30 seconds.
Why the hype?
As computers act more and more as hubs for portable electronics, current ceilings on transfer and connectivity speeds become more and more of a burden. USB 3.0, the "superspeed" serial bus, gained traction on some devices last year, but has yet to be adopted widely. Apple could leap frog USB by co-opting the faster and potentially more versitile Light Peak for its MacBooks, similar to the way it used IEEE 1394, or FireWire, in the '90s.
FireWire became popular with audio/visual equipment, but never achieved the kind of universality that USB did. Intel designed Light Peak to be truly universal, and if they're successful, you'll be able to use Light Peak, or "Thunderbolt," to connect virtually all of your peripherals at light speeds.
Winning the connectivity wars means Intel will have to find a lot of cooperative partners. The company is planning a press event in San Francisco for unveiling Light Peak tomorrow, and a concurrent roll-out at Apple's MacBook Pro announcement would be just the kind of high profile introduction the nascent technology needs.