A month or 3 back, Mailinator was averaging about 1 million emails per day. Now its running pretty solidly at 2.5million+ (see the front page sidebar for the realtime number). Spammers are really going wild.
One peak I happen to notice was 171,000 in an hour, that's ~47 emails per second. Not bad for one little AMD 2Ghz server considering it also handles many thousand web and rss requests too. (who says Java is slow?)
I rewrote the whole system from scratch a year ago (SMTP server and all) as using stock linux services (sendmail, apache, mysql, etc) started dying at less than 1million a day. Monitoring tells me there's plenty of room left before I need to think about another server. Keep em' coming.
I know the spam surge has been reported elsewhere, but consider this my own empirical evidence.