Is There an IT Talent Shortage?

I keep hearing that there's a huge shortage of IT workers.  That there are businesses hiring, and they can't find good people.  I did notice in the last round of hiring for the team I'm on that it was hard to find good candidates.  It was difficult to get resumes in, and it was tough to find candidates that met our needs and got through our screening.  (Note: we were very lucky and got some great folks for our team in 2012, so I know they're out there)

Note that it's not 1999 anymore.  People are not reading a single book on HTML and landing a high paying job with a single interview that only really asked if you were breathing and could type an angle bracket or two.  People are not moving from job to job, year over year, and getting a 10% salary increase each time they move.

That said, when I hear that there's a shortage of IT workers, and I hear the unemployment numbers, I am not certain I know what I'm hearing.  Is it that the IT worker rate of unemployment is that much lower than the general population rate?  Or are there plenty of IT workers that simply can't find work, or are in the wrong location.

There's another explanation, and I'm hoping someone can fill me in (comments, email, twitter, whatever), and that's there are IT workers out there out of work, but not willing to work in the positions that are offered.  That is, are there more senior people available out there than junior people, but the openings are all for junior people (or vice versa)?

Is it that the companies can only afford junior level pay and openings and the demographics of the available worker are wrong?  If that's the case, doesn't that eventually have to put upward pressure on salaries, and push businesses to offer the positions out there that can be filled?