At the moment, Google will be turning its 60 privacy policies into one unified system on March 1st. This will consolidate all data on all of its products, including Google+, Gmail and YouTube, into one policy. There will be no option for users to opt out if they wish to use any of the company's services.
The new policy does not seem to meet European law in terms of protecting the privacy of the individual under the European Data Protection Directive. According to Reuters, the regulator has very specific concerns about the legality of the changes.
The CNIL and EU data authorities are deeply concerned about the combination of personal data across services: they have strong doubts about the lawfulness and fairness of such processing, and its compliance with European data protection legislation.
The French regulator is asking Google to put their planned changes on hold so it can send out a list of questions by mid-March on behalf of itself and other regulators in Europe. There is no indication at this stage that Google will do this, having refused to delay after earlier concerns were raised twice before, although it has said that it will answer regulatory questions.
A New York Times report states that the French agency can warn and fine Google and issue court orders to suspend violating practices if it does not adhere to privacy laws in the country. This would not work Europe-wide, as each country may have its own regulations. At this stage, the switchover on March 1st is unlikely to be stopped by this investigation and it is not yet clear if the French action will have any future effects.