Statement of principles from the Libertarian Socialists:
The Libertarian Socialist Movement organizes anarcho-communists who believe in class struggle as a way to overthrow capitalism and oppressive state power. The LSM adopts the aspirations and demands of the working classes, industrial workers, small farmers, wage earners, proletarians, and anyone who does not have ownership over the power of his work and sells it without control to the production process.
We believe in the practice of direct democracy in neighborhood assemblies and communes and in the boards of commissioners of cities and provinces on the basis of mandated temporary powers, not authorized decision making powers, but within the framework of decisions taken in advance in the neighborhood assemblies and communes.
We are against the capitalist ownership of the means of production, and against all forms of paid work, we strive for the development of production units under the self-management of workers run for the benefit of society as a whole, including the full needs of the community.
We believe in a network of enclosed cooperatives linking productivity and self-managed production units, consumer cooperatives and community-based managed services including elimination of the parasitic activity of intermediate trade.
We believe in the right of the community to full control of all natural and financial resources in order to achieve their needs.
We believe in the right of society to create self-protection units, management and local accountability.
Our main program is: liberation of the workers from the yoke of paid work: from each according to his abilities, to each according to his needs.
(Translation by Tahrir-ICN)
From here
You know what, it's been such a long time ago since I was studying these things that I can't remember exactly. It may have been in some of Oliver Roy's work (e.g. the Failure of Political Islam), but could also be a specific article from some journal I can't remember. I do remember, however, that the reason the MB took such a shape was because very early on islamists, while in universities, would brush shoulders with leftists organizations. Not only did organizational structures rub off, but also a lot of the terminology. If I remember correctly, there was no word/concept of "revolution" (as we understand it) in Arabic until quite recently (whether that is the case for "al thawra", what I know as revolution, I do not know). Indeed, the islamists apparently invented a whole vocabulary based off the Marxist-Leninist dictionary. So sorry, not much help there. But I think a decent social history of the MB should cover it.
What Entdinglichung said and what's on that wikipedia page chimes with what I remember from researching political islam during my undergrad and while living in Egypt.