What's the first web 2.0 product of microsoft?

Because of the unexpected shutdown, my outlook can not start up and it's trying to fix the storge files behind.

then I open IE and use OWA( outlook web access). as expected,there are lots of junk mail,:)so I press delete one by one, the email are dropped . however ,the screen does not refresh ,seems it send the delete command asynchronously. and the request/response reveived are kind of web-formatted xml. so Is owa the first web 2.0 app of microsoft?

<?xml version='1.0'?><D:move xmlns:D='DAV:'><D:target><D:href>http://Server/exchange/mmmm/Inbox/%E4%BB%8A%E6%97%A5%E7%84%A6%E7%82%B9-%E2%80%9C%E4%B8%96%E7%95%8C%E9%93%B6%E8%A1%8C%E6%95%B2%E5%93%8D%E6%96%B0%E5%85%B4%E5%B8%82%E5%9C%BA%E8%AD%A6%E9%92%9F%E2%80%9D.EML</D:href></D:target></D:move>