It looks like any concerns about the way VADA drug testing works have been ironed out for the UFC 152 fight between Rory MacDonald and B.J. Penn. VADA had originally offered to "sponsor" the fight by providing their drug testing services for free, something that Penn and MacDonald agreed to.

However, Penn decided he didn't like that VADA released their testing results immediately, meaning that the fight would likely be cancelled if either fighter tested positive during the eight weeks of random testing leading up to the bout. Penn insisted that the results should be held until after the fight was completed. I called Penn's condition "absurd" at the time and pointed out a whole host of reasons why VADA couldn't bow to B.J.'s craziness.

And it looks like they haven't, but that testing has been salvaged (via VADA's website):

MMA fighter BJ Penn has enrolled in the VADA (Voluntary Anti-Doping Association) program and will undergo 8 weeks of random blood and urine testing for his UFC 152 bout taking place in Toronto, Canada on September 22, 2012. He has agreed that all test results will be immediately forwarded to the ABC (Association of Boxing Commissions), the Ontario athletic commission (Office of the Athletics Commissioner), and the UFC.

MMA Junkie said that they confirmed with Rory's camp that he will also participate in the testing.

This would seem to be great for the sport. There's been a need to improve the drug testing protocols used in combat sports for quite some time as the Athletic Commission testing is quite lacking.

VADA had to stay strong on not holding results back for a number of reasons, both legal and ethical. That they didn't back down speaks highly of their commitment to their "mission."

Of course, we've already seen some boxing promoters whose fighters had embraced VADA testing previously start looking for "alternatives" because VADA was effective in turning up positive tests for fighters like Lamont Peterson and Andre Berto, resulting in two highly anticipated fights being cancelled.

So, the question is: if VADA testing is effective in catching fighters who are using PED's, but results in fights being cancelled, would the UFC be interested in having future fights also have VADA testing? Or would they also "look for an alternative"?