Not too old. I only found out in early November myself.
There have been rumours of this for a while now, but looks like it's true if it's on the Crypton site. Judging by the sample songs there, we won't be disappointed.
The one thing I'm wondering about is why she has an 03, when Len is supposed to be 03.
Oh, well. The family grows to seven, the technical family grows to nine!
Alright, some clarification. I can't believe I didn't notice this sooner.
That's not on crypton.co.jp, which is Crypton's main site. That's the site for UTAU, which is a bunch of vocaloid spinoffs made by veeery dedicated fans.
That means Yokune Ruko DOES exist, but not as one of the actual official Vocaloids. Someone's done a pretty good job of spreading the idea, though.