As far as I know, there are no Nokia devices available or announced that have support for MIDP 3.0. It seems that the specification hasn't even received the final approval:
http://jcp.org/en/jsr/detail?id=271
For information about Nokia devices, I second the link provided by laalto. It also has a search, to filter devices based on a certain feature, such as supported Java APIs.
About the question about classification you added: Java ME is the umbrella covering many different mobile Java technologies. The Java ME specifications most relevant to mobile phones are the CLDC and MIDP. MIDP is the one that contains most of the APIs visible to the developer, so that's often referred to as the platform like you suggested.
However, the "Java ME SDK 3.0" you referred to is a specific product from Sun, containing tools for developing for MIDP and also some other Java ME platforms. Despite the version number of the SDK, the MIDP tools contained do NOT support MIDP 3.0. I don't know if there are any tools available for developing for MIDP 3.0 yet, perhaps someone else has more information about that?