It's true that you could build a condenser and pump the steam through the next batch of water, but I doubt you will ever get anywhere near the efficiency you need to make it reasonable. I'd be incredibly happy to see any links that would prove me wrong, though!
That's really cool. Thanks! I should point out, though, that I meant that I don't think you will get efficient enough to make solar power reasonable. You will notice that Hitachi's RO solution has higher power efficiency than the distillation solution. I'd be really curious to see how much power it actually uses, though... Unfortunately it doesn't say in their marketing material.