Meteor uses mongodb for a database, with an API available on both client and server, which handles caching and re-drawing the page when data changes. The server is a wrapper around Node.js, to allow for JS everywhere. Coupled with auto-reloading of pages when the source changes, this looks like it makes for a nice development environment, although it seems like it would be easy to cripple application servers or databases if not handled with care. Their approach seems to be to hide many implementation details to ease the learning curve, which would be risky in a demanding client environment, as it’s nice to know how things work if you have to fix them.
The notion of smart packages as designed is interesting; the idea is to allow you to run a build target which adds a sophisticated feature to your project; e.g. support for single sign-on integration, email, LESS, etc, with appropriate defaults and deep feature-sets. The demo-ed features looked cool, although the Meteor team is working to improve the ecosystem of open packages, to the point of taking ownership of projects that community members start to fill gaps, but can’t maintain.