Over on WWE.com, they have announced that the SmackDown Tapings on Tuesday, January 9, 2008 in Lafayette, LA has been rescheduled due to "scheduling conflicts". They have rescheduled the show for June 8, 2009, which will now be a RAW taping. Though no announcement has been made regarding where the SmackDown Tapings will be held on January 9, one would assume that WWE will be holding another dual SmackDown taping the prior week in East Rutherford.
Also, WrestleZone.com is reporting the following is regards to the January 20 tapings:
WWE had scheduled a SmackDown taping to take place on January 20th, 2009 in Cincinnati, Ohio, however it has since been canceled in favor of a double taping which will take place in Omaha, Nebraska the week before on January 13th. The ECW taping which was originally scheduled to take place prior to the Cincinnati taping of Smackdown has now been moved to the night before where it will be taped prior to Raw.
So it seems that WWE is making this a new trend in order to save money on television tapings. This may be a new permanent format in the forseeable future.