With the release of Lync it is likely you have assumed that LWA means Lync Web Access just like CWA meant Communicator Web Access, turns out that it means Lync Web App. To further the confusion the web app is not providing Instant Messaging and Presence (IM&P) but instead it is a meeting client.
To date, I think the best explanation of this topic is from Tommy Clarke, one of our MVP’s.
Here is the url for his post - http://www.ultimate-communications.com/2010/09/lync-web-app-explained/
and I will copy/paste the most common question I get on the topic, what can I do?
<excerpt from Tommy Clarke’s Lync Web App Explained post>
LWA is now a Silverlight based meeting client and not a chat IM client like CWA was. But what if you want to just IM people from a internet coffee shop? Well there are still some options.
1. Upgrade your exchange to 2010 and you can have IM sessions from Outlook Web App.
2. Use an old CWA server (good for all those iDialog users)
3. Build your own client.