phone programming WORA?

Is there anything Write Once and Run Anywhere for cell phones? I'm
doing Java on Android and looked at Java Mobile (J2ME) but it seems
each phone vendor has their own UI. Is that right? Someone else told
me to try Mono and it has translators and compilers to all platforms.
Is that true? Then there's Symbian and the iPhone. What about them?

I'm thinking about taking this iPhone boot camp course:
http://iphoneclt.eventbrite.com/ but it just seems like too many
platforms to try to target. It says "The iPhone Development
Accelerator (IDA) course is specifically designed to take you from
zero to a working application as quickly as possible. " but I need
something like this for all phones. Does such an animal exist or is
everyone just writing for one phone or what?

Thanks!
TimJowers