Like everyone else that I ever have a disagreement with on the subject ...
That estimate by bitcoinwatch is simply the average block increase/decrease since the last difficulty multiplied by the the current difficulty.

When I last checked it 5 hours ago it was +11.27% ... then times 2190865.9701029 = 2,437,777
Of course that changes all the time - but anyway, there are no special estimations done by anyone who calculates those ... they are simply multiplying a rather (extremely) unreliable figure times the current difficulty.

i.e. take an average over a list of blocks and assume that will be the average at the end of the the difficulty
i.e. assume that the hash rate doesn't change and that you cannot see a pattern to the hash rate change

Anyway ... yes I'm not trying to get anyone to give me BTC - so don't even think of it

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Meanwhile, I added to cgminer's API (not available in any version yet though) to show information about the pools ... specifically roll-n-time information.

I currently have 6 pools in my list (5 as backups - one of them solo of course - a a few of them have multiple entries) and to my surprise there where 2 pools who do not advertise roll-n-time (other than my solo bitcoind)

Deepbit (of course) and ABC ...

Anyone where at ABC gonna fix that one day?

https://bitcointalk.org/index.php?topic=28402.msg1111327#msg1111327