Here's why, in no particular order, we think the Extensible Messaging and Presence Protocol (XMPP) will rock your world soon:

• Real-time web applications are in high demand, and XMPP fits the requirements perfectly -- it excels in rapid peer-to-peer or broadcast messaging.
• Response times are crucial for the new breed of web applications, and polling-based solutions are very suboptimal. Enter XMPP and BOSH.
• The maturing of the BOSH protocol, coupled with the resurgence of excellent Javascript libraries have, IMHO, opened up extremely cool new worlds via the browser. Strophe, in itself, is a treasure.
• XMPP servers, which are essentially make or break an XMPP application, are rapidly maturing beyond instant messaging. Especially eJabberd.
• It's possible to deploy a custom eJabberd module based on the XMPP protocol but tailored specifically for your application in a matter of hours. The initial learning curve is offset by the rapid development speed of the Erlang language (thanks to its immutability) afterwards.
• While there's a lot of focus on developing pure web applications, as of now nobody has figured out a great way to make money off the Instant Messaging protocol. This will be a boon for XMPP development very soon as new startups try to tap into that market.
• The web framework wars are slowly winding down, and in the end developers are left with the classic problems -- many will now be turning to alternative tech for the problems that most web frameworks don't even attempt to solve; XMPP is the solution for many of these problems.
• The community, albeit small, is growing and passionate. Extremely passionate. Search for XMPP on Twitter. The mailing lists are very active as well.

Apart from all of these, as a developer I find writing XMPP applications to be a very engaging and enjoyable activity. Word will spread, and there will be new converts. At Intridea, we've been actively developing and integrating XMPP into our products, and we will be leveraging it on a case-by-case basis for our client work. You'll be hearing more about that shortly.