EA have announced
that Battlefield 3 has sold over five million copies in its first week of release, making it the fastest selling game EA have ever had. It's interesting to note that a big part of the press release focuses on the stability of the online experience:
Server stability was solid in the first weekend, delivering EA’s highest-ever usage rates. While some players experienced intermittent outages of online services due to high volume, internal estimates show that servers and service uptime stabilized to roughly 98.9% throughout the weekend, ensuring that players were connected and enjoying the game. With a commitment to support the game as a software service, EA is listening to consumer feedback and is making daily updates and improvements to ensure an optimal online experience for all.
We've asked to find out what proportion of those are PC sales, but publishers are usually notoriously tight-lipped about that - so we'll see.