The last time I wrote about Dirk Karkles, we learned that "do your best" is not a managerial plan of action.
Dirk Karkles thinks he can pay attention to more than one thing at a time. For example, he thinks he can write a report and carry on a phone conversation (or an IM/IRC session) at the same time. "I'm multi-tasking!" he says, sometimes with pride.
To this I say: There is no such thing as multi-tasking, there is only attention-switching.
You cannot perform two or more non-trivial tasks at the same time; at best, you pay attention to one and mostly ignore the other, then you switch your attention to the other and dismiss the first one temporarily, and then you switch your attention back to the first again. This is far less effective than completing the first task, then moving on to the second task, because of the time and mental effort it takes to switch between tasks.
Attention-switching is particularly bad when you are in real-time or near-real-time conversation. If you are doing other things while talking with someone else by voice or IM/IRC, you're telling the other person they are not worth your full attention. If they're not worth your attention, why are you worth theirs? ("I'm the boss" and "I'm paying them" and variations thereupon are not valid arguments -- try again.) You are wasting your time, and theirs, by not being a full participant in the conversation.
Now, there are times when you must give your attention to multiple tasks. Be aware that you are not multi-tasking, you are attention-switching, and take this into account when you switch your attention to another task. At the very least, you will need to take time to "catch up" on the task before you perform some new action related to it. For example, in an IM/IRC conversation that you are taking active part in, you will need to read and comprehend the backlog of messages before you you can even think about writing a meaningful response. Among other things, this means that attention-switching is not a net time saver, it is a net time spender -- but sometimes you have no other option.
So, the next time some tells you "I'm multi-tasking!" you know that person is not paying full attention to anything he's doing right then. Similarly, if you find yourself attention-switching in live conversation, have the common courtesy to excuse yourself and pick back up again later, when you can give it your full attention. "Multi-tasking" is something to apologize for, not to be proud of.