This Battlelog Post announces this will be a double-XP weekend for Battlefield 3 (thanks BF3Blog). Here's word on how you can work smarter, not harder in the military shooter sequel:

Here’s a great chance to rank up faster and have great fun while doing it. This weekend, we are running a new double XP event for everyone! On June 16-17, your sum total for every round will be effectively doubled, visible at the End of Round screen. This applies to any map and any mode, as long as you play on a ranked server.

You can see the full details of this event below. Basically, play Saturday and Sunday to rank up faster! And if you’re a Battlefield 3 Premium member, you already have access to the Close Quarters expansion pack and get double XP on those maps as well.

What: Double XP event to celebrate the launch of Battlefield 3: Close Quarters
When: 00:01 AM PDT June 16th – 11:59 PM PDT June 17th
Formats: All
Criteria: All players, both Premium and non-Premium members
Servers: Any ranked server
Game modes: Any
Maps: Any (including base game, Back to Karkand, and Close Quarters)
What: Double everything!

Wait! What time does the event start where I live?
Consult this handy chart!
Los Angeles: 00:01 June 16
London: 8:01 AM June 16
Stockholm: 9:01 AM June 16
Tokyo: 4:01 PM June 16

Not Premium yet? More info about Battlefield 3 Premium can be found here