Basically a up-vote in a question or answer means it is clear and useful, but I feeling people are not giving so much importance to that.
Are Q&A not being so good as expected?
In my opinion, there should be a few more downvotes, not because we want to be mean, but because we desperately need more depth to the site. Downvotes communicate that the answer or question is not a good question or answer.
If you read the FAQ, downvotes can be changed to upvotes if the question or answer is edited and improved. They're not permanent, and we shouldn't be afraid to use them as a tool to help this site make it past beta.
We should also leave comments with a downvote to help the OP or answerer improve. If the question or answer is improved via constructive edits, then please consider voting up the question or answer.
I would say that the reason there hasn't been a lot of voting is related to this meta question es have a core essentially pleading with people to avoid broad and beginner questions.
The beta is composed of a core group of subject matter experts reading and evaluating some incredibly basic questions. If their reaction is 'ho hum', I'm not surprised. It's only been a few days and we're already collecting 'Best of' questions. Yeah, I answered it ;-) but I wouldn't expect people to up vote it. But they do.
That said, I think the goal should be to try to write great questions and provide thoughtful answers. I prefer to see the SO either accept an answer or update their question with a reason why after a reasonable amount of time, but lack of votes one way or the other doesn't affect me much.
Wouldn't it be due to the amount of users we currently have in the community?
Checking all time users, there's around 20 users with 1k+ reputation. On the top of my head, thinking of 'active pm users', I just remember a dozen of names, which are actively participating on the forum.
Let's think half of them consider a question really useful, and we'll have around 5 upvotes.
On a glance, the most upvoted questions could easily have come from search engines... and besides, it's not a huge amount of upvotes, either (28 votes so far on the most voted question).
So, I'd say it's not a matter of discussing in meta why questions are not being upvoted. Most of the folks around meta are upvoters (I guess, hehe). It's a matter of spread the word about pm.stackexchange.
One more thing: I'd guess that part of a forum activity evaluation could be based on the average of users / up + downvotes. This information could be compared to other SO forums... then we could know how slow/fast we're growing.