A new Battle.Net FAQ on the Blizzard Website offers images of the new version of Blizzard's network interface-cum-marketplace. There are details on how this will impact various games, including how WoW players will eventually be forced to migrate, confirmation the service remains free, and word the marketplace will offer (presumably paid) content. Here's a bit:

What will be available to players in the StarCraft II Marketplace?
After the launch of StarCraft II, we aim to add the StarCraft II Marketplace to Battle.net, which will create a vibrant ecosystem of user-generated content, including multiplayer maps, single-player scenarios, challenges, themes, and more.

How will Battle.net affect my multiplayer StarCraft II experience?
We’ll be implementing a new auto-matchmaking system, with advanced skill tracking to allow players to be matched with other players of similar skill level. This will help players consistently face evenly matched competition. We’ll also be implementing various leagues and ladder systems to allow a more competitive StarCraft II landscape.

What is the Real ID feature?
Real ID is at the forefront of online gaming as it will allow you to easily connect, communicate, and play with real-life friends. Connect with old friends and current guildies, and make new friends with the integrated Battle.net social networking tools. Beyond simply seeing your friend’s character names (e.g. “Gorlac” in World of Warcraft or “Snip3r” in StarCraft II), and having to remember which character name goes with which friend, you will be able to see your Real ID friend and chat with him or her across Blizzard games. What’s more, Real ID is totally optional -- the options are there for you to build your Blizzard Entertainment social network however you see fit.

What are some of the communication tools available in the new Battle.net?
Our vision is for the new Battle.net to become the ultimate Blizzard Entertainment social network, in addition to its matchmaking foundation. Simply logging in to Battle.net will make it easy to find and chat with your friends across World of Warcraft, StarCraft II, and future Blizzard Entertainment titles, including Diablo III. Keep track of all your buddies in your friends list, view their online status and presence information, voice chat, send out party invites, and broadcast messages to your friends. Detailed character profiles let players keep up to date on friends’ progress and achievements.