The front for the Muslim Brotherhood are: the Council on American Islamic Relations (CAIR), the Muslim Public Affairs Council (MPAC) and the Islamic Council of North America (ISNA). In addition, the Muslim Student Associations in Colleges throughout the US are fronts for the Brotherhood. Yet: all these organisations are viewed benignly by the American public and media and accepted as legitimate religious associations (when in fact they are political bodies) and, in the case of CAIR and ISNA they are the "go-to" guys for spokespersons representing allegedly "moderate" Islam in the US. Their aim however, is the same as that of the Muslim Brotherhood, for that is who they represent. They have set out a "General Strategic Goal" for the Brotherhood  in which the aim is to "settle" the US and that...
The process of settlement is a "Civilization-Jihadist Proecess" with all the word means. The Ikhwan [Brothers- ref 2] must understand that their work in America is a kind of grand Jihad in eliminating and destroying the Western civilization from within and "sabotaging" its miserable house by their hands and the hands of the believers so that it is eliminated and God's religion is made victorious over all other religions. Without this level of understanding, we are not up to this challenge and have not prepared ourselves for Jihad yet. It is a Muslim's destiny to perform Jihad and work wherever he is and wherever he lands until the final hour comes, and there is no escape from that destiny except for those who chose to slack. But, would the slackers and the Mujahedeen be equal.If I'm criticised as being a conspiracy nut, I will make the following point: that conspiracies usually involve secrecy and intrigue. While there's intrigue with the Brotherhood, there is no secrecy. They are very clear on what they want to do: "... eliminating and destroying the Western civilization from within and "sabotaging" its miserable house by their hands and the hands of the believers...." What can be clearer and more open-transparent? And if we dismiss them as a bunch of extremist loonies, we should think again. They have been a powerful force since inception and no government, not even Egypt when it was most keen to do so, has been able to crush them.
The Brotherhood is in the US. It is there via the organisations listed above. Each of these organisations is cozy with the US government and the US media. These are facts. Should they not be cause for concern rather than casual dismissal?
Update 2 Dec '11: The slogan of the Muslim Brotherhood:
Allah is our objective
The Prophet is our leader
Koran is our law
Jihad is our way
Dying in the way of Allah is our highest hope.
Ref: Ayaan Hirsi-Ali
 An Explanatory Memorandum on the General Strategic Goal for the Brotherhood for North America. Mohamaed Akram, Shura Council of the Muslim Brotherhood, May 1991. This document also contains a list of all Muslim Brotherhood organisations in North America as of 1991. (Ref here .)
 Who are these people? Interesting little article on it here . The picture above is courtesy that blog, and calligraphy means "In the name of God". June 24, 2007.
 The Muslim Brotherhood Project. I don't think this is a "Protocols of the Elders of Zion" for Muslims. The provenance seems sound. It seems "kosher", as it were.