Since they're already starting to promote it (actual marketing, not just screenshots/demos), I'm guessing it'll have a late 2015 (holiday) release. Prepare your wallet.
It better have co-op. I love FO3/NV, but it gets so lonely and stale. Borderlands style co-op would be a huge improvement.
T&Cs quote from the bottom of the fallout4.com website
Use of this Web-Site without sufficient understanding of Science may result in death. Always consult your Vault Overseer for guidance on appropriate Web-Site usage.
Is there any indication where they're going with FO4? I ask because I didn't really get into FONV; I didn't like the crafting aspect of the game and, for me, it got boring real fast.
According to the BBC, a Gamespot guy expects an updated FO3 with "a few new elements".
But the BBC also say they think the dog will be controllable. If they mean companion, then probably. If they mean playable character controllable then the guy who wrote the article is a fool.
And of course, the BBC is the best source for game related news.