I'll do my best, but you should really click the links K0ilar and robotl suggested as they'll do a much better job of explaining than I'm about to.But by far the best coverage I've found today is the live-streaming coverage by Al Jazeera English. I've had it open on a separate tab for a couple hours while surfing and blogging; there hasn't been a commercial yet, and they are offering a mix of interviews with analysts and live video from the streets and commentary from reporters down in the streets and up in buildings.
The Catalyst: Tunisia a country in Northern Africa was ruled by a repressive and dictatorial regime led by President Ben Ali. At the end of 2010, a series of riots broke out throughout Tunisia, collectively termed the "Jasmine Revolution." The root causes are considered to be mass unemployment, widespread corruption, appalling living conditions and the governments propensity to squash free speech. This resulted in President Ben Ali dissolving the government, a victory for the revolutionaries.
Regional results: In the region, the success of the Tunisian revolution led to widespread instability. It had previously been considered axiomatic that regional dictatorships were too stable to fall. The Tunisian revolution proved otherwise and soon protests began all over the region, most strongly in Algeria, Yemen and Egypt.
Egypt: The Egyptian youth were mobilized by the example set by the Tunisian revolution. Many suggested that the upcoming 25th of January 'National Police Day' be instead used as a massive nation wide protest against corruption. Other causes for the unrest have been the widespread brutality of the Egyptian police and military (Egypt is basically a dictatorship because the country is under 'Emergency law' and has been since 1967), the crippling poverty in the country and President Mubarak himself.
The Egyptian Response: The Egyptian police and military have been very heavy handed in responding to the protests. A huge number of protestors have been beaten by police and plain clothes secret police officers. Three have been confirmed killed at the time of this writing. In an effort to stop the protestors utilizing Facebook and Twitter to organize and get their message out, Egypt shut down access to those two sites and now, basically unplugged the country from the internet entirely.
Friday: This Friday will see a pivotal moment in the Egyptian revolution as a mass protest has been called after traditional Friday prayers. The Egyptians have called for a "Million Man March" but the chaos in the country and the unpredictability of what's going on makes it difficult to even guess at what will actually transpire.
Predictions: Analysts are split as to what will happen in Egypt. There seems to be a concensus that unlike Tunisia, whose military was underpaid, had terrible morale and had little stake in the Police State, the Egyptian army is far more likely to support the Mubarak regime. If the support of the armed forces wavers (as the police support already has, on occasion) then a very real revolution is on the cards.
The U.S in the Region: If you're American and wondering, the U.S has a lot of skin in the game. Mubarak has received a huge amount of aid from the United States. Egypt is one of the only Middle Eastern countries to have something approaching a lasting peace treaty with Israel, and Mubarak is generally considered to be a 'friend of the West' by the standards of his fellow leaders in the region. Many of the protesters see the U.S as propping up Mubarak's regime. If the revolution succeeds, any popular democracy in Egypt is almost certainly going produce leaders with anti-American platforms. Further, one of the largest opposition groups in Egypt is the Muslim Brotherhood, which is considered a terrorist organization and a supporter of terrorism by the Russian Federation and is typically anti-west in its rhetoric.
Hope that helps and I really hope I didn't get too much wrong.
I don't know how to embed this live video. You can watch it/listen to it at this link.