Well, MC is just the renderer, what it can do is all down to the users and crunching those numbers. For example, a while back I was doing something similar in Visual Basic 6, I wanted random textures for planets, but I wanted them to be dynamic. Couldn't find anything online that would do what I wanted, so I had a go myself. Not perfect, but close enough for what I wanted it for, and nice to adjust the settings to see a planet change from ice age to cooked wasteland.
Those screenshots of that Testworld are impressive (love that that person is using Misa textures
)
One suggestion though is don't blur the biome edges all the time. Have a config setting to control it, sometimes it's nice to have conflicting biomes next to each other. It does happen in the real world due to rain shadows, atititude and many other factors.
I saw also mention somewhere about making it so that the further north or south you go (towards minecrafts poles), the colder it will get. That's good, but if this happens, make it configurable.