If you want more background to the story, click here and here but long story, short-- Wolf videotaped a bunch of anarchists get with the anarchy, a cop was hurt, Wolf showed it off, the Feds got involved and Wolf begged off saying that the Feds have no reason to want to look for the tape as it's a local matter. Thus the jail. It should also be said that the U.S. attorney on the case, Kevin Ryan, is stepping down and all the remaining criminal cases related to the case have been dismissed. Except for Josh's case.
The latest in all things Josh is that yet another motion was filed to get him released and like the others, was denied by Judge Alsup. His mother is actually in Capitol Hill today to try and rally support for her son.
You can see footage of the event here and the Josh Wolf Wiki lists various ways to help. NBC 11 has not only an interview of him but bits and pieces of the original video. Wolf is expected to be in jail at least until July when the grand jury that subpoenaed him expires.