A report from the Financial Times claims that Google and Opera "informally provided the tip-off" that led to the EU fining Microsoft over $730 million yesterday. The fine was levied because Microsoft failed to include a "browser ballot" screen that let European users choose what browser to use when setting up their Windows PC. The Financial Times cites "several people familiar with the case" as confirming that Microsoft's browser-making rivals were behind the tip, and claims that both companies also helped the EU throughout the investigation.
Although uncorroborated, this revelation makes sense: both Google and Opera benefited heavily from the inclusion of the browser ballot, and Opera has been a vocal opponent against Microsoft's tight integration of Internet Explorer with Windows for a long time. When asked for comment, Opera told the Financial Times it was "happy to see that the Commission is enforcing compliance with the commitment, which is critical to ensuring a genuine choice among web browsers for consumers." Google was also asked for comment, but declined.