I don't think there is anything wrong with upvoting your own posts, after all it is on by default and some users may not even be aware that they are voting for their own post. Voting for your own comments can get a bit cheesy. I was contemplating voting this one up full strength to see how I would feel... lol.
It is an interesting social experiment for sure since we all stand to gain from building community. It does feel good to vote for others but without a certain amount of self interest and investment your vote does not do as much.
It's only really bad when it's extreme. I have seen one recent user posting tons of comments with very little content, all self-upvoted for $5+... unfortunately there's not much I can do about those things.
Spreading the wealth and cooperating is a very good thing. I think there used to be some guidelines around this like giving a certain percentage to the church or community of what you earned.
If you ask me there is nothing really we can do about this self voting (except flags) because any technical solution can be gamed. Besides I really feel it is much better if people can find their individual choice and do as their heart guides them in this issue because we have no way of knowing all the things they may have experienced or are going through.
As they say in Zen, "Greed, hatred, and ignorance rise endlessly, I vow to abandon them." It's much easier to simply let these things go than try to cut them down.
In any case since I never posted anything today, I'm getting the happy feeling of posting up my comment. Hopefully voting your comment up too will give you a happy feeling. :)