Im thinking of terrorist groups like Al-Qaeda and the like. Is Wahhabism part of their ideology? If so is it related to the spread of Wahhabism as a result of the massive oil revenue Saudi-Arabia saw from the 50's and onwards.
This is not my area of specialty, but here is some information until someone more knowledgable gives you a better answer.
Yes. Wahhabism/Salafism, as you probably know, is a very conservative, fundamentalist interpretation of Sunni Islam. Side note: my professor for a course in the development of radical Islam made the point that practitioners prefer the term "Salafi" as opposed to "Wahhabi," which they view as derogatory. Also important to note: most practitioners, while holding views antithetical to many of us in the west, are still not Jihadists. Nonetheless, Salafism, and the Hanbali school of jurisprudence, forms the bedrock of most modern radical Islamists world views and interpretation of Islam.
Here are some sources to give a much better answer:
"Jihad: the Trail of Political Islam," by Gilles Kepel
"Jihad in Saudi Arabia: Violence and Pan-Islamism since 1979," by Thomas Hegghammer
"Sayyid Qutb and the Origins of Radical Islamism," by John Calvert