I was able to find the trending myself just a few minutes ago:
Why is it a hot trend? We're not sure, but Sphinn members hope that it's because the character is a religious Hindu symbol (or Chinese character).
Forum discussion continues at Sphinn.
Update: A Google spokesperson gave us a statement:
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.