Why has Unity answers moved and what has it gained?

Answers has moved to QATO because because Stack Exchange changed their bussiness model and started charging a monthly fee for the usage of the software. Sure there are a few teething problems but I'm confident that in a week or so they will be ironed out.

GesterX is almost right. StackExchange who hosted the "old" site changed their business model. They wanted all sites like ours to go through their Area51 process, and that doesn't work for Unity. We have lots of plans for how we want to improve the community sites, and working with dZone was the most efficient way we can do that. The "old" site was scheduled to be shut down completely on 13th April. We got an extension whilst we migrated, but the old site would have blinked out of existence at some point.