Q: How do we make sure the hard questions get as much reputation as the easy questions? I find this question a little more pertinent now, given Stack Overflow Careers and Joel's assertion that reputation is a good indicator of programming ability.
The majority of my reputation comes from either insanely easy questions or meta-ish questions. Sure we have the meta thing policed, but what bugs me is the huge difference in "plus rep" you can receive for providing pretty simple responses in popular technologies (such as C#) against excellent answers in more niche ones.
I've seen awesome posts in niche techs that have like + 30 tops, whereas there are others that are kind of "meh" in a popular technology with +100 or more. 
Is there anyway we could adjust the voting system to address this? Bounties help a little, but I was thinking more along the lines of being able to +x an answer or even gift reputation to others for specific answers that really helped. 
Update
I appreciate that answering the question in the title is the obvious thing to do but I'm much more interested in discussing systems to address this issue that don't also open up other cans of worms.
For example, if we had a feature where I was allowed to give an extra 100 reputation to an answer per day because I have greater than X reputation where would such a feature fall down?
Or are we agreed on the premise that such a system is impossible, and the current one is the one that "sucks least"?

A: Is reputation a good measure of knowledge?
Obviously, no.
How do we make sure the hard questions get as much reputation as the easy questions?
I don't think it matters.  Reputation and question difficulty are unrelated.  The system as currently implemented allows bounties for those really hard questions, but other than that there is no need to award harder questions with more reputation.
They either get answered, or they don't, and that's the point of Stack Overflow - good answers to reasonable questions.  Reputation is just the carrot - it turns Stack Overflow into a game with a leaderboard, and encourages people to play.
Once you make reputation dependent on a subjective measure, such as "difficulty" then the control loop (the carrot egging the programmer on) becomes unstable without very, very, very careful adjustment and damping.  
I believe adding more subjectivity to a scoring system will not only result in a worse outcome, but will actively drive some programmers away who currently enjoy being 'graded' using relatively objective measures - you are either right or wrong.  A lot of programmers hated English not because they had difficulty with the language, but because you couldn't turn in a paper and know in advance if it is objectively 'correct' or not.  
There's still a ton of subjectivity in the current system, but we already have plenty of complainers about spurious downvotes they don't feel are deserved.  Do we care to face the onslaught of, "The question I answered should have been rated difficult because it was hard for me!"

A: Totally agree with what Joel Coehorn says.  Time spend is the major driver behind my reputation :)
In addition, high rep depends on how (for lack of a better word) "hot" your answers are.  An answer to a simple C# question can get you tons of upvotes.  Because it's simple, many people feel confident that your answer is right. And many people follow the C# tag.
But in the job market, the opposite is true.  The "colder" your knowledge is, the harder it is to find, and the higher your market value.  How many people answer SAP questions here?  Yet SAP positions are among the higher paid in the industry.
I wouldn't be surprised if high reputation is negatively correlated with salary.

A: It has a lot to with luck.
Can you get your well reasoned and crafted answer in there with at least one up-vote before anyone else?
If you can then your answer appears first on the page and is more likely to gain more up-votes. There have been discussions on this - search for "Fastest Gun in the West" and now answers of the same score are randomised rather than being presented in chronological order, but once an answer starts getting votes it's much like a snowball rolling down hill and gains more.
NOTE This answer applies to the question as originally titled - I'm going to have to think some more about the updated version

A: Given equivalent behavior and areas of interest, rep can be a relative measure of ability, I think.  For example, if you had two users who answered questions in roughly the same tags and had roughly the same number of answers, but whose reputation level were an order of magnitude different (10K vs 1K, say), I think you could infer that the higher rep user had more ability than the lower rep user.  I doubt that you could say that they were 10x better, though.

A: The answer is... it can be.
There are many users that have gained a fairly high reputation by only asking questions... and fairly simple ones at that.
The best way to tell the difference is the questions asked to answers given ratio, the lower the better. Other factors are involved, such as the number of total upvotes on their answers, and esotericity of their questions (higher is better).

A: No.  There is some measure of ability (you'll have a hard time getting a high rep without it), but it's also a lot to do with how well you can express yourself in writing and even more to do with have much time you spend on StackOverflow.

A: Highly technical questions usually get low views because not many people are interested in them, especially if the user choose a good title.
StackExchange could choose to value up-votes more when a question has low views.
An up-vote could count +15 rep when 25% of the people who viewed the question choose to up-vote the question.
