The old 80 / 20 rule

Jeff Atwood suggests there are two types of developer. Basically it comes down to 80% of developers are what I would call plodders. They get on with the job, but aren't particularly brilliant or interested in coding as a craft.
The other 20% have a passion for developing and are not only good, but are always trying to be better.

Being a contractor, I have worked in a lot of different industries, and more importantly with a lot of different people. My observations of different types of developer are below.

Type A: Plodders

Plodders get their name because they tend to plod away day after day, producing code. The code they produce might not be the most elegant solution but it works and that's all they care about. These types never really better themselves too much, because programming is something they do to pay the bills and they don't really love it.
Every project needs plodders - tell them what to do and then let them go.

Type B: Coders

Coders are definitely in the 20% mark. They are very good developers, with the ability to look outside the confines of what they are doing and see the bigger picture. They would be keen to better themselves by reading blogs and books and keeping up to date with latest technologies. Coders usually need to be kept interested in, or believe in what they are doing, and can revert to plodding if they aren't. Coders would rather prototype something to see if it will work, rather than methodically work out what would be needed and document every part of the system before coding.

Type C: Careful Coders

A careful coder is basically a coder with a more meticulous personality. These types prefer to have a full understanding, and a fully documented specification before turning on the IDE.

Type D: Guru

These are very rare types, maybe 5% of all developers. They fully understand the languages and technologies they use, and know things inside out and can wring the last CPU cycle out of their code. A true guru isn't self titled. It's up to other developers to give them that name. I've worked with maybe 2 or 3 in my entire career.

Obviously the above list is entirely subjective and only coming from my experience but I think most people would agree that the guys around them would fall into one of those categories above.

For the record, I consider myself to be a coder, but always seeking to be better and improve so one day I might come close to being a Guru...