No idea what kind of pepper (light yellow...hint of purple?)

Man this looks like a very rare case in which your peppers did not grow true to the original plant.
 
Honestly, this seems like you may have hit that one-in-a-million freak chance and that this plant is a "freak of nature" and has a recessive gene for a WHITE phenotype.   
 
Save the seeds of this plant and grow them out again and see what happens. If this pepper was grown from the same seed pack, and you're sure that the seeds weren't mixed up somehow, I'd say you grew a pretty cool mutation. Sometimes the phenotype, or the appearance, of a white pepper can have a yellow-ish hue to them. The purple looks to be marks from the sun.
 
Another thing to think about is prolonged ripening, which can happen when the plant is undergoing too much stress. How much water is the plant receiving? How often? Has the plant been growing at all? Doing anything out of the ordinary?
 
 
The only true way to determine if the pods are ripe is if you cut the pod open and look at the development of the seeds. If the seeds are super soft, the pod is not ripe. Compare the taste of these pods to the other ripe ones.
 
 
Post pics! This is interesting
 
 
 
Below is an interesting chunk of information I found on dominant and recessive traits in genes. Just imagine that the comparison is with pepper color and not eye color.
 
 

What are dominant and recessive alleles?

Different versions of a gene are called alleles.  Alleles are described as either dominant or recessive depending on their associated traits. 

• Since human cells carry two copies of each chromosome[SIZE=14.4px]?[/SIZE] they have two versions of each gene[SIZE=14.4px]?[/SIZE]. These different versions of a gene are called alleles[SIZE=14.4px]?[/SIZE].
• Alleles can be either dominant[SIZE=14.4px]?[/SIZE] or recessive[SIZE=14.4px]?[/SIZE].
• Dominant alleles show their effect even if the individual only has one copy of the allele (also known as being heterozygous[SIZE=14.4px]?[/SIZE]). For example, the allele for brown eyes is dominant, therefore you only need one copy of the 'brown eye' allele to have brown eyes (although, with two copies you will still have brown eyes).
• If both alleles are dominant, it is called codominance[SIZE=14.4px]?[/SIZE]. The resulting characteristic is due to both alleles being expressed equally. An example of this is the blood group AB which is the result of codominance of the A and B dominant alleles. 
• Recessive alleles only show their effect if the individual has two copies of the allele (also known as being homozygous[SIZE=14.4px]?[/SIZE]). For example, the allele for blue eyes is recessive, therefore to have blue eyes you need to have two copies of the 'blue eye' allele. 

Illustration to show the inheritance of dominant and recessive alleles for eye colour.
Image credit: Genome Research Limited

Shape-wise, they curl a bit but a few of them look exactly like the stock photos of Vipers I've seen. The purpling looks to be tanning at the intersection. Not at all uncommon in the stems of supers, less common at the top of the pepper like that but probably still the same phenomenon.
I'm not the most experienced grower but would definitely call those white Vipers.

Just got home and it's dark out on a holiday weekend, but sometime tomorrow I'm going to pick a ripe red  viper from the other plant and snap a shot with them side by side....then cut the white viper open and see if the seeds are mature then post some more pics. 
 
To answer some of obeychase's questions, the plant is not under any other stress than all of my other superhots are under...the main difference is that this plant is in a large pot (maybe 10 gallon) while the others are in a raised bed. I water them about every other day...sometimes every 3 days depending on if any plants are drooping a tad. I live in Alabama and its 92F+ last couple weeks, and will be for another 2 months. This particular plant seems to have grown it's base stem shorter than the other 2 plants, so it branched out lower on the plant initially. Keep in mind I pruned some plants earlier than others to experiment.
 
I'll cut the pepper open tomorrow to see the maturity of the seeds in it, but there is no over ripening, as the peppers were the same color even when they were pretty small. I'll give some more feedback and pics tomorrow.
 
Thanks everyone for trying to help me shed some light on this particular plant! Much appreciated!
 
Cheers
 
Nate

Here is a quick side by side of 3 naga vipers, each one from a different plant from the same seed packet. As you can see the weird one is in the middle.
 

 

Hmm, how did the seeds look? How does the pod taste compared to the red ones?

this is very cool..learning about genetics  via peppers!

PMed you a while back and have heard nothing. Would love some seeds.

spicefreak said:

PMed you a while back and have heard nothing. Would love some seeds.

Click to expand...

 
same here!!

obeychase said:

same here!!

Click to expand...

Same here! Would love to pop these in my hydroponic

I have some of the exact same thing going on with some ghost peppers! I saved seed last year from some purchased peppers and grew them. Every plant is producing peppers that look like what you're experiencing. I was at our state fair (MN) yesterday and visited for a while with a guy that had a pepper/hot sauce booth. I showed him a picture of my ghost peppers and he claims that they can definitely look like that.

White/Black Ghosts are more of a known occurance than white Vipers but they're the same phenomenon. Apparently black Ghosts have never bred true but white, being a recessive gene, should always show up in offspring from self-polination.