The answer to this question is a tiny bit more complicated than you might think.

The Controversy

The main problem comes in the form of semantics, because bison and buffalo are two different animals, though many people use the terms interchangeably. Even Wikipedia says the following:

A white buffalo or white bison is an American bison possessing white fur-Wikipedia

Did you catch that? Shortened up it's "A white buffalo is an American bison".

The Birth

A ranch in Burnett, Texas is home to a new, rare white bison. It is the offspring of two blondes. The birth was in April and that's early enough in the year for some to say, "Good times are ahead". So is a white bison a white buffalo, and possibly an omen of some sorts?

The Myth

Generally the white buffalo/bison is seen as a sign of peace, but it often goes deeper than that. Lakota legends say that the appearance of a white buffalo means the great spirit is hearing your prayers and that prophecies will be fulfilled. I guess we cannot, not mention the song by guitarist/provocateur Ted Nugent who wrongly portrayed the "Great White Buffalo" as some kind of symbol of vengeance, or comeuppance for those who mistreated the other buffalo (It's hard to say definitively what his message was).

It's All Good

Whether you believe the Lakota, Ted Nugent, or even superstitions, the birth is great news. Bison were nearly hunted to extinction but are now making a comeback, so any bison born, white or not, is a very good thing.