W/could wizards use Braille to write their spells to confuse their enemies?
AFAIK, the rule does not specify which language or letters must be used for writing one's spell book. So yes, if your PC can read/write Braille, he can use Braille to write his spellbook, provided Braille does exist in your game world.
But I also say that by RAW it will take only the usual effort to decipher other wizard's spell book whether if the book is written in Braille or not. Because, again, it is not specified if the spellbook must be written in letters common to the readers when one tries to decipher other wizard's spellbook.
Maybe, your DM allows you to make a spell book which needs Decipher Script check in addition to usual way to decipher magical writings, provided Braille is not so popular in your gaming world AND your PC pays some special cost to learn such a un-popular way of writings (and maybe extra pages needed for writing each spells). But still, by RAW, lower-level spells such as Comprehend Languages will easily allow enemy wizards to read it.
Remember that even a spell book written in geometric glyphs by Geometer prestige class (Complete Arcane) can be deciphered by other wizards in usual way, only with slightly higher (+5) difficulty.
At the same time, taking Geometer prestige class and just change the flavor, I mean, claiming that your "glyphs" are actually Braille, may work, too.