All you need to do is login and click on manage your Google Alerts. Then you can set up new alerts or modify current ones to be via RSS. Here is a screen capture of several RSS based Google Alerts I set up, plus at the bottom, I show how to add a new RSS version:
Pretty neat! Google just made reputation management just a bit easier for many folks.
The one disappointment might be the fact that the web search results are not set for auto-discovery as some were expecting. But this is a huge improvement of Google Alerts and I'll take it.