It is over, but not in a traditional sense. I mean, I still receive loads of junk mail daily but they all go straight to the "Spam folder" so I never get to see them, pretty much as if I had never received them. Spam is just something I don't care anymore.
For me, it's quite clear now that Spam filters have beaten spammers, hands down. Of course you need to use a decent spam filter but, frankly, who doesn't? (when Gmail already provides an excellent one). There are also very good open source alternatives such as spamassassin and dspam, the latter which I've found extremely efficient. So, if you ask me, Spam is over. Sorry spammers, you've lost. Now let's focus on more important issues such as Net Neutrality.
Also, like I said a couple of years ago, Jabber will converge with email in the future (it's already happening with Gmail/Gtalk) so communication will require a previous "synchronization" phase between the parts where their must authorize each other, and that will hurt Spam very badly too.