Ok... But then wouldnt it be their advantage to show more precise figures? As now people are aware what 51 % attack is and this kind of graph could just add to overall negative news to bitcoin.
From where organofcorti gets his data ?!=)
blockchain.info has lots of graphs. Most of them have incomplete/inaccurate information. They have no interested in showing precise figures because the data they're generally showing is just noise, it's not meaningful. Their distribution graphs for example only go to *at most* 4 days. That's an extremely small time frame, and due to the random nature of solving blocks, those graphs move drastically even though the actual hash rate distribution is fairly static.
Most pools sign their blocks in the coinbase. Blockchain.info doesn't seem to reliably use that information, contributing to lots of unknown. Some private companies always mine to the same address which is publicly known, but blockchain.info doesn't care.
Previous attempts by pool owners to get them to correct their information have always been met with silence. Some pools (BitMinter is a common one) constantly have blockchain.info showing that pool mining a block they didn't actually mine, causing miners to think the pool is cheating them.