The rate at which technology changes. I spend a lot of time trying to keep up with everything and it's difficult for me. This will forever be remembered as "the summer of Office 2007", for example.
As a lot of what I do involves software training, I don't always have as much time to focus on computer hardware innovations. However, this is one I really would like to check out personally. A virtual keyboard. Really.
A virtual keyboard picture from ThinkGeek.com
How does it work? It projects an image of a keyboard on to ANY flat surface, and you would then type directly on that flat surface. So, for example, you could plug this in to a Palm Pilot or something and have a full keyboard that just projects on to a flat surface, such as a table. For a business traveler, this is definitely a better option than carrying around a full keyboard.
Check the full description out!