Nicholas Kristof says the pro-Mubarak Egyptians clashing with the anti-Mubarak masses today in Tahrir square don't feel like a grassroots phenomenon:

In my area of Tahrir, the thugs were armed with machetes, straight razors, clubs and stones. And they all had the same chants, the same slogans and the same hostility to journalists. They clearly had been organized and briefed. So the idea that this is some spontaneous outpouring of pro-Mubarak supporters, both in Cairo and in Alexandria, who happen to end up clashing with other side — that is preposterous. It’s difficult to know what is happening, and I’m only one observer, but to me these seem to be organized thugs sent in to crack heads, chase out journalists, intimidate the pro-democracy forces and perhaps create a pretext for an even harsher crackdown.