
Email is a “catch-all” for every type of communication. What has happened is it has split into more functional technologies: RSS feeds replace list servers, instant messaging replaced the instant communication and social networking replaced the distribution lists.
There are many applications that can be used to send someone a private file without using email - Google Docs, DropBox, SugarSync, ADrive, Flip Drive, Flickr, Picassa, Zoho, etc. Also, all of these programs provide you with more storage space than you could ever use, they allow for version control, give you networked backup, web access to your files from any computer with an internet connection on the planet and let you publish documents and share them with whomever you like.
Twitter, Plurk and other microblogging tools are great ways to send quick notes people and social networking applications (Facebook, LinkedIn, etc.) are far more advanced messaging services than our ancient email friend.
One of the latest statistics reports out of the Nielson camp states that communication through social networking is outnumbering emails sent. Nevertheless, the numbers of emails sent haven't drastically reduced.
With all that said, I can confidently say that email is far from a dying breed. I think I can convince you with one simple rhetorical question: Do you invite someone to lunch by e-mail or Twitter?