The seemingly populist revolution in Tunisia appears to have touched a nerve in Egypt, where it's brought out an entirely different political culture than most Americans see depicted. "Western" perception of Egypt seems rooted in the Six Days War and the Nasr Presidency - with Egypt as a nation trapped in a religiously-imbued nationalist fury, typified by extremists like the Muslim Brotherhood. The existence of several notable Egyptians within contemporary international islamist organizations hasn't helped this.
But as some have pointed out, the basis of this populist uprising, at least in Egypt, is avowedly secular and what little involvement there has been by organizations like the Muslim Brotherhood has come after decades of negotiations which have largely resulted in them abandoning violent tactics. Likewise, others have suggested that recent anti-Islamist events have played an instrumental role in creating a secularized Egyptian identity. In all, I think we can be emphatic that this is not an Islamist event, at least not currently.
You'll have to weigh your conscience on this, but I signed this petition urging the US to at least get nominally involved against the government. I think there's valid concern that the US actually getting involved might damage the credibility of protesters (like in Iran), but I'm not convinced that it's quite the same situation - Iran is well known for perceiving itself as highly unique and highly victimized by American interests, in ways that I don't think Egypt can compare. Still, a gamble.
(EDIT: Live coverage from Egypt, here)