Is email on the way out? That is probably not yet an easy question, but the amount of spam seems to be holding steady, with periodic bursts of spam email storms.
Here are some graphs of spam at one of my mailboxes. This is for a very public email address. The spam detection is using spamassassin which runs under procmail with a customized whitelist and blacklist. Over the few years I've used this, there have been only 1-2 false positives for spam (of course, detection of false positives is not easy since this requires digging through 100s of spam messages, but I have no reason to believe that false positives are more prevalent). There have been quite a few false negatives - messages that are spam, but missed by spamassassin. These are usually around 1%-10% of the total detected spam messages, which is low enough that the graphs below are still useful to show the trend of spam message counts.
2010 Spam Counts 
The Spam Counts images are updated periodically, usually every day, to include data of the previous complete 24-hour period.
Older Spam Counts
The data from the graphs above came from procmail log files that were filtered using a perl script. The graphs were generated using a command-line php script, using the extremely versatile JpGraph - PHP Graph Creating Library.
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