Background: UBS agreed to hand over names of its American customers to the Swiss tax authorities for disclosure using routine information-sharing provisions of the tax treaty between the United States and Switzerland. A Swiss court found that agreement to be an unlawful attempted modification of a bilateral treaty without Parliamentary approval. (Just as U.S. treaties must be approved by the Senate, so must treaties be approved in Switzerland by Parliament).
We are now in the pre-game show for the Parliamentary action. The agreement [PDF] has been gussied up to make it as constitutional (under Swiss law) as possible prior to presenting the issue to Parliament.
Now it is End Game. The largest opposition party has said it will object to ratification by Parliament. It does not have enough votes to block ratification by itself.
(Personal note: the Parliament building in Berne is every bit as beautiful as it appears in the official website photo.)