According to this article on ESPN:
There are plenty of particulars to iron out, like the date (probably sometime in April), the venue (none has been chosen) and the promotional and broadcast partners to be involved (Elite XC, CBS, and Showtime, with perhaps some other co-promoters), before what is believed to be the first brother vs. brother faceoff in fight history becomes a 100 percent done deal.
"We've both signed a contract to fight each other," younger brother Frank Shamrock told ESPN.com. "Ken is down with it. We talked about it two years ago, and we've agreed materially to fight."
"Will the fight happen? Absolutely," Ken Shamrock told ESPN.com. "He's got a buttkicking coming to him. Everything I've learned, everything I have bottled up in me, is going to come out on him. I've still got love for Frank, but I'm angry at him."
The article is kind of misleading in that they say the fight contracts are signed, yet it's still not 100% confirmed. We also have to take into consideration of what promotional banner this fight will take place under. If it is to take place under the EliteXC banner, will they still be around in April of next year? There seems to be a lot of details to iron out, so don't hold your breath on this one just yet. Umm, I'm really not trying to see this fight.