Python has been around as long as Java, but it is a scripting language that tends to be used in a different problem-space, so it's not entirely a fair comparison - each has its pros and cons for different purposes. Ruby has been around a long time too, but my impression is that it is mostly used in web apps with Rails, and Rails is probably less suited to big enterprise stuff than Java. So again, you're comparing apples and oranges. And there are plenty of other scripting languages that are widely used - PHP, Perl etc.
I guess if you're only going to learn one programming language, it should probably be Java (or C/C++ which really is everywhere under the hood). But expecting to get by with just one language would still be stupid. The reality is that different languages and platforms are suitable for different purposes, and they all change and evolve over time. Pick the language that suits your problem, and be prepared to keep learning new stuff.
As for "rising stars", you could keep an eye on the Thoughtworks technology radar for ideas:
Thanks Chris. I had heard about the Thoughtworks company before and I also saw some books by them. Just wondering if they are considered an authority in the IT industry, like Joshua Bloch is considered and authority in Java. I'll keep an eye on their blogs if there is a lot to be learned from them.