[narcissus]

OK I must be missing something here: how can any of the large pools have 51% of the mining power?

How can you have more than one pool, each with more than half the power?

EDIT: OK I see where you're coming from I think... you mean any of the pools could 51% the forked branch, right?

[SolarNet]

Yes 51% of the branch you are attacking. They have hard forked, any bitcoin mining pool could easily control 51% (like 80%) of the bitcash mining worldwide.

[pimlottc]

I assume it means any of the larger pools in Bitcoin could switch over to one of the smaller altcoins and overwhelm the much smaller pool of miners there.