From F4wonline:

Dana White confirmed today that UFC is running a show on April 17th, head-to-head with the announced Strikeforce show on CBS.  The event would air most likely on Spike TV.  The Wanderlei Silva vs. Yoshihiro Akiyama match is not the main event.  The only thing confirmed is they are trying to finalize a Matt Serra vs. Mike Swick semifinal fight today

I mentioned yesterday that the Kimbo Slice/Matt Mattrione fight had been removed from the UFC website and could potentially be James Toney's first UFC opponent.  If that doesn't take place, then it's a very good possibility that Slice could end up fighting on this Spike TV event.  The guy is a ratings draw, and his fights on spike almost beat the last Strikeforce card on CBS in regards to ratings.  That's simply incredible considering that CBS is available in way more homes than Spike TV.  Also, Wanderlei Silva potentially fighting live on Spike TV?  Wow.  I criticize Strikeforce for a lot of the things I think they do poorly, but this is a prime example of why they should be around.  Otherwise, we would not be getting a choice of MMA events on the 17th.  Now it is possible that Strikeforce could move this CBS event to the 24th and go head to head with the WEC 48 PPV, but that hasn't been announced yet.  No matter how you look at it, Strikeforce will have competition for it's next show but it will not be re-hashed programming like the last time Zuffa counter-programmed their event.