I'm actually the most excited about JodaTime basically being baked into the language. Date and Calendar are so, so bad that it would be hard for Instants to not be an improvement.
Why do people keep saying this? It's blatantly wrong, as mentioned multiple times by the JodaTime author itself.
Because one of the main authors behind JSR-310 happens to be the JodaTime author and considers it to be inspired by JodaTime, even if it's different to fix some flawed assumptions JodaTime made [1]. And as far as practical use goes, they're very similar, since they draw upon the same concepts. I don't see how it isn't a fair description, especially when you compare to how bad Date/Calendar are right now.