I put my email address in the clear on the web everywhere, and contrary to popular belief this doesn't seem to have any effect on the amount of spam that I receive. It's been stable at an average of 3 per day for a long time. So I'd say that obfuscation is useless.
I do notice that very short usernames (e.g. [email protected]) result in more spam. Apparently the email addresses used by spammers are simply generated by trying all possible short letter combinations, and by using name lists.