I have been working on getting Flash working well in Qt/Webkit on the N900. The hard work is done, you can find all patches here.
1. XEmbed support for the Flash on the N900 does not work very well. So, we just force windowless mode on all Flash.
2. Transparent flash is not supported and behaves the same as in opaque mode.
3. Opaque mode is implemented using the local rendering extension.
There’s some optimization work to be done which I plan to do next week.