Eurogamer has the story. In short:
As part of Blizzard's ambitious plans for the new version of the Battle.net online platform to launch alongside StarCraft II, the company's design chief Rob Pardo [has] revealed plans to allow the mod community to sell content on a StarCraft II Marketplace after launch.The Marketplace would be a forum for publishing and downloading both free and premium maps. "A portion of the revenue" from premium maps would go to the creator
It is unclear what criteria a map would be permitted to become "premium".
The news comes from Battle.net's general reveal at Blizzcon, which Eurogamer are also reporting. Alternatively, there's a video on Gamespot.
To me this just sounds like another way to milk money.. but hey.. if people are... well willing to do it.. I don't blame them for it.
I have to say though, I do like the fact that the creator of the map that is "premium" will get a portion of the money.
Let's imagine.
My friend is a genious map maker. He made an awesome map and wants to sell it. Blizzard allows him to. But as I mentioned - he's my friend and simply shared that map with me via internet/torrets/im/usb flash etc.
What will happen?
I'm sure that since you're friend is the author of the map, assuming it will be premium content, he will have full rights to give it away for free to who ever he pleases.