Sources: Tages Anzeiger (Zürich) and Switzerland public holidays. The leader of the SVP parliamentary group, Alfred Heer, has steered a bill through that would remove May 1st from the list of public holidays in the Canton of Zürich. The lost day would be compensated by a "joker-holiday" which could be taken at anytime by employees (and would allow parents to make it coincide with one of their children's 2 "joker" school holidays).
Reasons put forth for this bill include the assertion that the spirit of May 1st has become perverted, and that the Left has done nothing to avoid the holiday being taken over by extremists and hate-mongers. In addition, surrounding cantons are open on May 1st, meaning that business flows away from Zürich on that day.
Opposition parties are squarely against this reform and, having lost the parliamentary vote, are likely to try to force a referendum on the issue.