What is the significance of this horned creature that appears sometimes in Bejeweled Blitz?

Solution 1:

http://forums.popcap.com/showthread.php?626-stag&s=638eeb048932cfe891e8da45ccb9d23b&p=2901&viewfull=1#post2901

According to someone at PopCap:

The "stag" in the background that appears has no other significance other than one of our artists created a rather cool Autumnal scene to use for the game that has a sort of mystical quality to it. Everytime you hit a multipier, a new part of the scene is added. Kind of cool, huh?

So no, it has no meaning.

Solution 2:

It seems to only appear when you reach 4 times multiplier, as you increase in multipliers it disappears and the scenery changes, I have noticed it change to a purplish color