Being unable to focus can simply be a side-effect of being distracted, tired, or trying to learn something that really pushes your brain.

The fact that you have a hard time doing something does not mean you should give up on it.

Removing distractions is one technique. Kill your IM apps and work in a quiet area. You'll still feel like checking those distractions out for a while, but once you get into the groove you can work smoothly with little effort.

The other thing is that once you done some work, and you're getting tired and finding it hard to concentrate, take a break. You tend to work more productively when you're fresh than when you're weary.

I find that music helps keep me focused on the task at hand. I've got different playlists setup for my different developing moods. ie. learning, coding, designing, administrative, etc.

That along with actuall closing the IM, Email and IRC clients can go a long way towards helping you focus.

I also find that when learning something completely new it helps alot to have a small project to apply the new knowledge to. Even if it is something silly, it helps cement the new concepts in your long term memory.

Indeed, classical music helps me sometimes, when I feel like doing silly things, as opposed to study/research.