The specs has been standardized. Earlier threats of split Intel vs AMD/NVIDIA/(practically other chipset maker) has been resolved and are now unified and ready to go. At Intel's Developer's Forum (IDF Fall) in Nov 2008, an actual real life demonstration by Synopsys (a company making test equipments) showed streaming uncompressed HD 1080p video at 30fps at a transfer speed of 450MB/s (3.6Gbps). Although USB3.0 is spec'd at 4.8Gbps, 3.0 to 3.5Gbps is the real data transfer speed in practice.
So now equipment for development and testing is ready, cables are ready, it's close to product development time. Most estimates say 2010 or Christmas 2009. But we some optimists say prototypes could be seen at exhibitions in March or June 2009. In any case, early products would be high priced as there will only be Intel in the beginning. AMD/Nvidia (joint development) chip will be later, and the other chips have only just begun development.
Another indication of timeframe is Windows 7, the next release of Windows scheduled for Aug/Sep 2009 release is expected to support USB3.0. But Microsoft has said "it would be a challenge" to get USB3.0 into it in time for the release date, so it would likely be implemented as a Service Pack update after release.
That's what I know so far regarding time. At my work, we already produce USB3.0 cables (well people testing and developing USB3.0 products need cables right?!). However we also produce accessories (hdd casings, hubs etc), and for these I'm unable to put a date to it yet even though our company is committed to bringing in USB3.0 as early as possible.
Hope this gives some idea of the time frame. In short, for affordable products, 2010 is the year. But if you'll pay anything just to be the firsts to have USB3.0, 2009 is the year.