In my never-ending crusade against misinformation promulgated by anyone but myself, I refer to an article in the May 2006 issue of The Writer magazine. In a review of a book called What in the Word? Wordplay, Word Lore, and Answers to Your Peskiest Questions about Language, the statement is made that the author says the symbol @ "may be called a logogram or a grammalogue." Actually, the @ symbol is called the "commercial at" under the ANSI/CCITT/Unicode character systems. Logogram is a generic term for a symbol that represents a word or another meaningful unit of language called a morpheme--think Egyptian hieroglyphics or the written Chinese language. A grammalogue is basically the same thing--a shorthand symbol for a word. So technically, yes, the @ symbol may be called a logogram or a grammalogue, as it is one of many, many logograms and grammalogues, but those aren't specific names for the symbol.
There, I feel so much better now that I got that off my chest.