At least it's new for me, and it's not on the list. Bugged a colleague of mine today, and we were both very surprised for a while until we figured it out. Ok, it's not very complex, but the deal was that:
SELECT CAST(1 as CHAR)
SELECT CAST (1 as CHAR)
does not (syntax error!)
Now, CAST is already horribly limited in MySQL (who came up with the idea that you shouldn't be able to cast to all available types if it's reasonable to do the conversion?! Like from int to text...), but this is just too much. Since when does whitespace before a parenthesis matter in SQL?! Sheesh...
Yet another reason to prefer PostgreSQL...
Whitespace before parenthesis shouldn't matter, but MySQL allows reserved words to be table and field names, and the way it does that is by requiring no white space between the function name and its opening left paren.