Google’s statement on such attacks is as follows:
The Hot Trends list is automatically generated by machines and algorithms that detect hot or breaking queries. In this case, it appears that the html code for this query was posted on a popular internet bulletin board, which led to quite a few people searching to find out more about this symbol. The Hot Trends list reflected that surge due to people searching with this query.
Perhaps its time to allocate a few more resources to prevent these types of messages from being spread.