Parts of the WIsconsin Act 10 that stripped public workers of most of their collective bargaining rights have been overturned. We're still reading the judgment, there will be more soon. This is part of the joint lawsuit filed by WEAC, AFSCME, SEIU Healthcare, the State AFL-CIO, and others. The judgment is attached below.
Based on a very quick reading of the court's statement, it appears that they have ruled that the parts of Act 10 requiring annual recertification of the public unions and the stopping of automatic dues withdrawal are the parts of the bill that have been found unconstitutional. This results in large part from the Walker administration's separation of public unions between the public safety workers and other employees. The argument seems to be that there was not a rational justification for this distinction, and that it could easily be read as a preferential treatment for those unions that supported Walker in the election since the police and fire unions were much more supportive of Walker than the general unions. There is also no evidence that stopping union members from paying their dues through payroll deduction is of any economic benefit to the state.
This does, however, leave the door open for the state to pass new legislation that doles out the same unfair treatment to all public employee unions. Note that this ruling also does not restore collective bargaining rights for the state employees, which was allowed to stand.