Judging by your question, I am assuming you're planning on mastering one of the above said frameworks. If that's the case, the answer is yes (i.e. you're going to put in a non-trivial amount of time AND effort).

Here's how I did it the last time I tried something similar: 1) Grab a decent book with plenty of sample code that builds towards a working product. This way, you get to see the moving parts and the theory. For Rails, Hartl's railstutorial.org is excellent - you build a twitter clone. Their much older book RailsSpace is pretty good too. While you're at it, checkout tryruby.org.

2) After doing 1 above, now pick a project and get building quick. Use the sample code from above and tear it apart.

3) 1 and 2 works really well if you do it with someone who is already either proficient or interested enough in going through the exercise with you.

0) Well, 1-3 would go a lot smoother if you already know another language or two, some decent background with data structures. Of course, that's not necessary, but useful nonetheless.

4) Regardless of what happens, keep plowing ahead. You will hit random errors or whatever. Keep with your schedule - "Finish chapter 4-6 today or whatever" and soon enough you can definitely finish the book in a week or two. Then the following two weeks is where you will learn the most with your own project!

42) You definitely will know enough to do something non-trivial, but again mastery depends on your case. As a friend of mine says, "anyone can learn to spit out a few words together, but writing an elegant sentence (or solution) is not that easy always... same with programming"

Good luck!