I have yet to meet a really competent programmer. I don't consider myself much beyond capable - but I have too many flaws in my output to be considered really brilliant.
I have worked with or dealt with the output of other programmers who's performance was egregious - most egregious was the contractor who's naive use of a commercial java framework managed to produce the effect of a memory leak in java (e.g. hamstrung java's built-in garbage collection mechanism).
Experience has taught me practical measures of quality programmers in no particular order:
1. They must know how to program at the most simple level (e.g. competency in structured programming in C would be a good starting point - a basic understanding of LISP programming a plus) before tackling more complex programming tasks. I get the sense there are a lot of cut-and-paste programmers out there who really don't understand what the underlying code they are creating is actually doing.
2. Have an innate ability to focus on simple solutions, rather than being clever. KISS principle must be understood and brought into every design decision from the start. That is not to say there are no complexities, but understanding what is simple given the problem at hand - some simple things are complex when compared to other systems - and having the ability to avoid needless complexity.
3. Literate - must be able to not only communicate effectively externally - but also their comments in code should illuminate the subject matter in a clear, concise manner. Ideally should be able to get workable technical documentation straight from their comments - via doxygen or the like (perldoc, pydoc etc).
4. Their code must be maintainable and extendable. If an average programmer cannot maintain the code, and is required to rewrite the system from scratch - then you have failed as a quality programmer. Change is inevitable - how resilient your system is to change is a measure of your ability as a programmer.
5. They must understand a lot about technology outside of the world of their application. Their application will live in a world of networks, machines (physical and virtual), storage systems, communication protocols, and APIs - they must understand the implications of software design choices given a set of environmental requirements. The best programmers not only know how to code up systems, but also how to give advice about what their systems will be capable of doing given the environment, or lack thereof - and act upon that if it is possible to adjust via changes to software alone (e.g. choosing multithreading/multiprogramming design over single thread of execution).
6. They must be able to create secure code. If the company they work for doesn't produce a guide to that, then they should develop that on their own - and live by it - and consistently improve it. If they are using frameworks/libraries written by someone else, they should audit or test it to be sure the underlying implementation is secure.
7. Must be able to get along with others and work as part of a team; ideally if they are really a quality programmer, I would expect them to also mentor and share their ideals and capabilities with their peers to bring everyone up as much as possible. Quality programmers are not primadonnas.
That's it from my standpoint.