No. The list of meta characters is (from programming perl):
 \ | ( ) [ { ^ $ * + ? .
These are the only characters requiring a backslash in a regular expression. I'll add the delimiter / to that list, if its part of your string.

Disclaimer: Obviously, if you do something like m!!, and then want to find an exclamation mark, then you'll need to escape it. Also, under that circumstance, you won't need to escape a /

Update: athomason adds a good point, be sure to read the next post too.