Build clients for LCS using... well, whatever spins your wheels...
In December last year, the Live Communicatons Server 2005 team released a browser-based client called Communicator Web Access that enabled you to expose your LCS messaging infrastructure to web-based clients, either inside or outside the firewall. This client makes it easy to deploy IM solutions that don't require the user to install a client - just use point the browser at the CWA server, and away you go.
The LCS team took this a step further last week, with the release of the new Communicator Web Access AJAX Service SDK. This is a very cool toolkit that allows you to communicate with the CWA infrastructure using AJAX, making it a cinch to build browser-based applications that can manage and share presence information, manage contacts and groups, and send and receive Instant Messages.
The SDK ships with a client-side sample app - written entirely in HTML/JS, as well as a forms-based application written in C#. The APIs are entirely JSON-based - outgoing requests and events being returned from the server side are expressed as JSON objects, which means that you can build a LCS client using any development language that understands HTTP and can parse text. So... client-side JavaScript is but one option - you could use C#, Java, Perl, PhP to target client-side, or server-side or both...
Combine this with LCS's ability to federate with MSN, Yahoo, AOL etc. etc. and you have the basis for a really open and extensible architecture for building rich interaction and presence directly into your web applications. Can't wait to get some time to play around with this!