Back in the days when we used to work in an office, setting up the projector for a meeting involved placing it at just the right angle, then hooking up the laptop to it, making sure there's a strong enough wifi signal, and praying to Cthulhu that it all comes together.
Now, with the Princeton PTW-PTS Wireless Projector Server, you can keep your computer where it is and move the projector—no need for wires! It supports a 1024x768 or 800x600 resolution and transmits using standard wifi. Install the software on your wifi enabled PC and it will stream video output to the receiver, which is plugged into your projector.
There's also an ethernet port available in case wifi isn't, but isn't that defeating the purpose? Unless you're using one of those 50+ feet ethernet cables, we suppose.
Available for order from Japan in mid June for $310.