What's so hard about delegate counts?

I'm clearly missing something. I thought that after a state's primary was over, you could know how many delegates each candidate had won. For the Republicans, I believe this count no longer matters; with Romney's exit, McCain's the candidate. For the Democrats, however, the topic is still of great interest.

So why do all the sources I've checked disagree?

Here's a sample of the problem, with all numbers being total delegates:

BBC News: Clinton - 1,045 / Obama - 960
CNN: Clinton - 1,033 / Obama - 937
CNBC: Clinton - 855 / Obama - 861 (I have to believe this one omits the superdelegates)
ABC: Clinton - 1,069 / Obama - 990

Note the variety in the above:

* No two have the same count for either candidate.
* One has Obama winning; Clinton owns the rest
* The total number of committed delegates is never the same.

Fortunately, that last site had an article with this useful explanation:

"Superdelegates are under no obligation to publicly declare candidate support, which makes counting them an inexact science."

It also explained the following:

"In addition to the pledged delegates, 796 'superdelegates' get to act as free agents and can select whichever candidate they wish for the nomination."

So, if this site is right--and I suspect it is--all the totals we are seeing, except perhaps the ones from MSN, are merely estimates. With superdelegates composing about 39% of the votes a Democrat needs to reach the magic total, these free-agent voters are both vital and, as these sites' totals show, hard to pin down.

You gotta love a simple system.