Yes, the group does have a website: HeartOfTheCity.org.
Many of these companies provide private busses that bring employees from San Francisco to Silicon Valley offices in San Jose, Cupertino, Palo Alto, Mountain View, and other cities south of the city. The Apple bus was the second such shuttle targeted by protesters, as a Google bus was stopped by the same group two weeks ago in Oakland.
Here's a video of Friday's Apple bus protest posted by Joe Fitz Rodriguez: