The short answer is yes. As the previous person mentioned, as long as you have the flash runtime.
HOWEVER, (polyglot speaking out) Adobe or the Flex community has quite a bit of work here to make it worth it for native-styled apps or apps on the phone itself. Yes, from a development perspective it would be nice to take the knowledge you already have in Flex and apply that to mobile apps, but would the final result really be better than what you can do with an Android native Java API or iPhone's objective C implementation? In my opinion, it's all about using the right tools for the job. I'm not saying it can't be done (so don't give me hell for saying so..), I'm just not sure it's best tool for mobile right now.
The good news is, Flex-based websites out there will benefit from newer smart phones that support Flash finally. This is a good thing. But still much more work to make Flex a viable option among various mediums.