I've abandoned all my Qt mobile apps simply because they won't be as long-lasting as I'd hoped. I was going to flesh them out over a few years.
I still have some Linux/Windows apps in QML just because it's so nice to program in. I will continue using Qt/QML on desktop.
I may look in to .NET programming for mobile. Even though I prefer Qt, I think .NET is the next best thing anyway. Unfortunately that will target only one platform (or perhaps 3 if you include Windows and Xbox).
But this will be a long way in the future as I do not desire WP7. In its current state it is a joke to call it a smartphone honestly. It's very fast and fluid but apart from some MS-only products that are integrated, its features can be compared to S40 dumbphones.
I'll keep an eye out on WebOS too. HP seems to be giving it justice. It seems to be like a combination of the best parts of Android (Linux kernel, OS, supports devs, do what you want) and WP7/iOS (flashy, fluid).
I don't know what they use for programming though - anyone? I heard MoJo is what they used to use (in WebOS 1.x,2.x) and they will still work but they are going forward with something else in 3.x?