Most covering letters sum up the CV. I don’t think that’s a good idea; why give a précis of the CV when it’s attached? You have to say something about yourself but what should it be? The best I have seen came recently, a letter from a marketing professional.
The first para was refreshingly honest; I have lost my job and I can join a new position at a day’s notice, or words to that effect. Most covering letters pussy foot around this issue; the fact is, a lot of people have lost jobs and there’s no shame in being upfront about it.
Then, in five well-written bullet points, the candidate summed up his skills. There was no bullshit, no hype, no exaggeration, just a straightforward statement of what he brought to the table.
And the letter ended really well, “Keep me in my mind if something relevant comes up”.
Spend as much time on your covering letter as on your CV. The two need to work together, and when they do, your chances of landing a good opportunity go up.