There are several different ways in which we communicate. The Linux Desktop can make this much easier than it already is.
Email is an archaic system that is still extraordinarily useful. Nowadays, I use Thunderbird 3 for my email. However, I believe there is a lot of work left with email.
GMail's innovative use of threading and including your own replies in the thread is a very good step in the right direction. GMail's search functionality is a major time saver as well. GMail also introduced the concept of tagging as the primary categorization feature. The simple filter is also a wonderful tool.
IMAP is one of those protocols that has taken a while to adopt but has been remarkably successful. However, I believe that it is quickly become less and less relevant since it was designed with the assumption of a file system behind it. A new protocol needs to be invented that would not only encompass email, but all communication protocols.
Email can no longer be stored on your computer. It must be stored in a place accessible from all of your devices.
Note that the email paradigm encompasses all the chat protocols, instant messengers, blogging, bulletin boards and micro-blogging. Even USENET has shifted to email. I'll discuss more in The Future of Email.
Our computers have become our phones now too. VOIP is quickly becoming the only way to communicate. The idea of picking up a phone and dialing in a phone number is going to be obsolete soon. We are going to pick up our computer and give it a voice command to call someone on our contact list.
We need a universal contact list. This would not only keep our private database of our contacts, but include public or semi-private contact lists, such as people in your neighborhood and church or people who work at your company. This contact list must be stored in a place where it is accessible to all of your devices, like your email.