Being a geek myself, I think this is a subject I think needs to penetrate all levels of management in every company that values their geeks. By no means is this a rant, but for the last 10 years I've seen what motivates us and what doesn't. I've seen the managers that just don't get it. I've seen those that understand completely and react accordingly. So, I thought I'd share my observations and see what everyone has to add as well.

1. Geeks are curious. Let them feed their desire to learn things
I don't know how much emphasis I can place on this point. You can take the ultimate geek...give them a rockin' compensation package...and give them "rubber-stamped" projects (same tasks over and over) for two years and they'll probably quit anyway. This point is based on the notion that if a geek feels his ability to gain knowledge is hindered, he'll try to find it somewhere else. Let them satisfy their curiosities with the task of picking up the latest technologies and applying them as they see fit. (Even if it's just for a prototype.)

2. Geeks like to be self-sustaining. Let them figure things out on their own.
I haven't met a true geek yet that wants you to hold their hand through every step of an implementation. In fact I've seen quite the opposite. They want to do things their way. If you suggest something, odds are the solution is wrong in their mind because it's not what they would have come up with first. There's many ways to complete a task in the technical arena, why cram your solution down their throats? Don't hinder their creativity, just let them figure it out.

The exception to this is probably in design. You obviously have to define your interfaces between components and have your requirements for the implementation. Let the details get figured out by whoever's doing the dirty work. You can optimize things later if they aren't up to par.