IM - Not a chance.
In case you've missed the memo, email is on the way out for casual communication. IM is what all the cool people use now. Now that I think about it, that memo was distributed via IM... so sorry.
If you have a gmail account, you have IM... -username- @gmail.com (protocol is jabber). If you have a yahoo email account, you have a yahoo IM account. And if you have a MSN account, you have a MSN Messenger account. Jabber and Yahoo allow offline messaging, which is pretty close to email. AIM doesn't do offline messaging, AFAIK.
So you have one of those accounts, but are sort of confused as to how to start using IM?
Get Pidgin. It works with all of them.
Email is still good for:
a) communicating with people who don't do IM, or at least not consistently
b) official communications (I don't expect corporate execs to IM each other proposals anytime soon)
c) writing long screeds (IM clients aren't geared toward word processing)
d) anonymous email (mixmaster and mixminion are damned good anonymizers, and are resistant even to NSA-level monitoring). Since IM is semi-real-time, it is more vulnerable to traffic analysis... like Tor.
Still, I would argue that b) and c) are better served by writing documents in a word processor, then either sticking them on the web and IMing the URL to the intended recipients or sending the file itself via IM. Email was never meant for word processing, and it pisses me off that so many people treat it as a medium to send html crap, PDFs, and word documents. At least with IM or IMed URLs the document-transfer process is out-of-band, and the IM correspondence itself isn't cluttered with that crap. Also, IM does away with the stacked-quoting nightmare that tends to occur whenever some non-trivial issue is being bounced around between multiple recipients.
And let's not forget the spam problem. It's much easier to spot spam via IM because there are all sorts of protocol peculiarities. First, all the protocols except jabber are centralized, which makes it easy to detect spammers and block them. In addition, decent protocols (i.e. not AIM/oscar) require permission to send to a recipient, so a message to a bunch of users who have not approved the sender is easy to notice, and easy to block. Even with jabber, which is decentralized, the same red flags go up if one jabber server is sending to a bunch of users on another jabber server who haven't set presence-notification for the sender(s).
In short, while I still do email, I think for most purposes, it's overused (and abused).
