Battlefield 3 may not have an in-game server browser on PC, instead relying on the built-in Battlelog. In response to a question about changing servers, DICE senior gameplay designer Alan Kertz suggests quitting out of the game completely and starting it up again.
The tweet answer (via unofficial fan site BF3 Blog) was in response to a pointed question ("why no in-game servr brwsr on PC"). In other tweets, Kertz says the Battlelog is the main menu, but then references using alt-tab. He also compared the method to Bad Company 2.
Even if going through the Battlelog is lightning-fast, it's a big change from traditional PC server structure that builds browsers into the main menu, and seems to force users to quit out of the game only to start it up again. PC stalwarts aren't likely to appreciate the hassle even in the most ideal of circumstances.
Shacknews has contacted EA regarding the fate of an in-game server browser, but has not heard back at the time of publishing.