While I can't vouch on whether the rumor is credible or not, it's worth noting that a bevy of websites are reporting that a description for the rumored Skyrim DLC Hearthfire has surfaced, claiming that the DLC will be dedicated to house building. Allegedly, the leaker would be the same person that previously leaked accurate descriptions for Mass Effect 3's DLC, which if confirmed, would make the rumor a lot more credible.
The topic on the Bethesda official forums has been deleted, but here's the transcribed description:
Hearthfire, the next official game-add on for The Elder Scrolls V: Skyrim, has arrived. For the first time in the Elder Scrolls universe, purchase land and build your own home from the ground up – from a simple one-room cottage to a sprawling compound complete with armory, alchemy laboratory, trophy room, and more! With Hearthfire, the possibilities of what you can build are endless.
Building houses doesn't sound like the most exciting topic to dedicate a DLC too, but I do know there are people that are interested in this kind of features in The Elder Scrolls title, so in case it turns out to be true and it's reasonably priced, I'd see no reason to complain.