most of us suspect late may to late june for the beta. i myself think mid-june.
we figured there would be more info about the beta in the may newsletter, but since there wasn't this pretty much guarantees something in the june one.
pretty sure someone on the dev team (mollygos probably) said they didn't plan to finish EVERYTHING about the game before releasing beta, because they wanted people to start playing it sooner for feedback and bug fixes etc.