USB 3 is showing up in premium notebooks and PCs but plenty of new PCs don't come with it yet - and if you're happy with your current laptop you wouldn't upgrade just for a faster device connection. As long as you've got an ExpressCard slot you don’t need to; you can pop in an adapter like the StarTech SuperSpeed ExpressCard and get speeds up to 5Gbps with USB 3 devices.
The card itself is an ExpressCard/34 so it's just 34mm wide, but the twin USB 3 ports on it are large and chunky, sticking out about two inches so you'd have to be careful if you left it in your laptop while you're carrying it around. If you need to power a USB 3 device as well (USB 3 can put out 5 volts and 900mA of power for large devices), there's a power jack on the side of the projecting section, but of course you then have to carry a power adapter too.
If you start off with just one USB 3 device the extra port isn't wasted; like all USB 3 connections, they're compatible with older USB devices.
Installation is simple in Windows XP, Vista and 7; slot in the adapter, load the driver and start attaching USB 3 devices. Sunrich doesn't seem to have Mac drivers yet; La Cie looks to be the first to bring USB 3 to Mac.
USB 3 memory sticks don't go quite as fast as 5Gbps; Kingston rates the 32GB DataTraveler Ultimate 3.0 we tested the card with at 80MB/second reading and 60MB/second writing. That's still fast enough to copy files the way spies do in movies. We tested the two USB 3 devices together and they're certainly fast. We did actually see a read speed of 80MBps with small files (and up to 86MBps copying to an SSD) but for larger file sizes it settled down around 65MBps. That's still a lot faster than the 20MBps you see with USB 2 drives (we compared the DataTraveler to Corsair's 32GB Flash Voyager USB stick and to other USB drives we had in the office and there's no comparison). Writing to the USB 3 stick peaked at 50MBps and was usually around 41MBps; with USB 2 flash drives you can expect write speeds of 5 or (if you're lucky) 10MBps.
That translates to under a second to copy 35MB of PDF files to or from the USB stick; it took 16 seconds to write 600GB of photos and 10 seconds to copy them to another hard drive on the PC, and 1 minute 43 seconds to write 4GB of mixed files (and 1 minute 3 seconds to read them). With USB 2 it takes 3 seconds to read 35MB of files but 15 seconds to copy them and you'll be waiting just over seven minutes for the 4GB set of files (or three minutes to copy the files onto your PC).
You're paying for the convenience of this speed. USB 3 ExpressCard adapters like the StarTech adapter are on sale for under £20 but the DataTraveler sells for around £80. The DataTraveler is chunky too - 3" long and almost half an inch square - but you are getting enough file space to make it worthwhile. You won't need USB 3 on every PC you want to use it with either. Kingston suggests using the supplied cable to plug it in to two USB 2 slots but we didn't see much difference between using it in a single USB port (although it did feel a little warmer to the touch when used in a single port). Either way it's about half as fast as a USB 3 connection for both reading and writing (which is still faster than other high capacity USB memory sticks we've looked at).
With the arrival of LightPeak still uncertain and eSATA on the way out, USB 3 is the next high speed interface you need. Unless you need to copy large amounts of files often enough to need the speed boost now, you'll probably want to wait until you get your first USB 3 device but when you do, you'll be delighted with the speed.