It's strange. Fox asked people on it's uk website to vote for the Irwin Allen shows of their choice for a DVD release over 18 months ago.
It started advertising Voyage and Tunnel a year ago, in flyers in with it's other sets.
Yet r1 has been announced. Nothing for r2; the Fox site shows releases up to the first week of April, and it's all Buffy and Angel (yet again - sigh).
I'm willing to bet that when we in r2 get these series, they will be full season sets, not half-seasons. That's what happened with Lost In Space (except we were ahead of r1 on those).
It could be that we won't hear any news of our first season until after the full first seasons have been out in r1. Of course, there'll only be one for Time Tunnel. I think it'll be May or June at the earliest.
I know what you mean, it;s frustrating, and you can bet as soon as you import the first Voyage set, they'll announce the r2 season, and it will look completely different!