I am giddy about this news: Laszlo is now Open Source. I haven't used Laszlo, but the demos and documentation smell a lot like Flex. I've been excited about Flash as an application view layer for a while, but have seen serious resistance to adoption for business reasons ("Macromedia? Like, the Dreamweaver and ColdFusion people?").
Hopefully, adoption will grow exponentially, and the new developer interest will lead to extensions. New UI widgets would be fun, but I really want to see disconnected clients. We're still a long way from critical mass acceptance of RIA, but between this and Gmail, it's becoming inevitable.
Props to David Temkin and the Laszlo team for such a brave move, here's wishing them well on the new business model.