Read/WriteWeb has a great summary of the new RIAs — Google Gears, Adobe Apollo and Microsoft Silverlight — and what they’re actually good for. These players don’t need to roll out more Rich frameworks, what is actually new about RIAs is that they work on- and off-line.
Currently one of the stumbling blocks to SaaS for small businesses is that they cannot be used offline, so if you want to read email on the plane and answer a few, you still need an app like Outlook. With an RIA, this is no longer so.
r/wW defines RIAs as:
desktop-like UI online, offline apps that look like online apps, and online applications that can go offline
a browser app with a rich user interface that has offline mode
browser app – but it works like a desktop app (e.g. a rich email browser app that works like Outlook)