Is it a better choice for someone new to both to learn Python 3 at this point or Python 2? Considering they are, in some senses, practically two different languages.

Personally I'd recommend learning 2 over 3 for the simple reason that one of pythons big selling points, for me, are some really great libraries and tools, which you won't be able to use if you use python3. That being said I'd focus on python 2.7, using the the back ported python 3 features and avoiding all the depreciated features. That way if and when you do switch to python 3 the shock will be lessened.

Most of these libraries are starting to get released as Python 3. I think Arch's push of Py3 has helped move things along. A good thing to do would be to "learn both" and help some people port.

Arch pushing Python 3 (or, as it calls it, just "python") definitely made me start porting Python 2 code to Python 3.

At least in my experience, they are pretty similar. Most of my Python 2 knowledge works fine in Python 3. I think it's really a stretch to pretend like your knowledge from 2 would be that divergent. I'm sure "in some senses" your statement is correct, but in practice I've seen few major changes. Learning Python 2 is the same as learning Python 3 and vice-versa; there are a few significant caveats between them, but I have never felt that they were "practically two different languages".

I was in the same boat last year, and I thought it would make sense to start out on Python 3. However, my intent was to learn Python to use Django. Django still isn't ready for that, so I'm using 2.6.

On the other hand, the text adventure game I'm writing for fun/as a learning exercise works great in Python 3, as it doesn't have any external dependencies.

Therefore, it depends if you're learning it for a specific use or just because you'd like to learn Python.

Read over http://docs.python.org/release/3.0.1/whatsnew/3.0.html for an overview on the differences. There are a few incompatible changes, but to say 2 and 3 are two different languages would be a big stretch.