Flash Lite will allow you to play Flash content on a mobile device, but it's not the same as having Flex on a mobile device. The kind of application development that Flex would give you on a mobile device is what JavaFX delivers (assuming you have a JavaFX-supported device, of course).
I cannot adequately describe how unbelievably cool it is to see your JavaFX desktop application running on a mobile device for the first time.
Sadly, mobile devices that support JavaFX are a little hard to find. Hopefully this will change within the next year.