The site reports that Fox wants Fassbender to portray a young Magneto in X-Men: First Class alongside James McAvoy, who will play the young Charles Xavier/Professor X. Columbia also wants Fassbender to portray the villain in the Untitled Spider-Man Reboot, although the site didn't reveal what specific character that villain would be.
While both are Marvel films, both are at different studios and Fassbender won't be able to do both films due to his schedule and will have to choose between the projects.
X-Men: First Class was released June 3rd, 2011 and stars James McAvoy, Laurence Belcher, Michael Fassbender, Bill Milner, Kevin Bacon, Rose Byrne, Jennifer Lawrence, Beth Goddard. The film is directed by Matthew Vaughn.
The Amazing Spider-Man was released July 3rd, 2012 and stars Andrew Garfield, Emma Stone, Rhys Ifans, Denis Leary, Martin Sheen, Sally Field, Irrfan Khan, Campbell Scott. The film is directed by Marc Webb.