I tried to learn Python last summer using the excellent book Learning Python by Mark Lutz, but failed miserably. Being proficient in another language, in which you can do almost everything you need, is a big problem. I would find myself setting out to solve a problem in python and after half an hour of slow/no progress, I would just switch to R and getting it done in a tenth of the time.
A different learning style seems to be key (for me at least). Well, finally the beautiful people at codecademy have answered the requests from thousands, and set up an online Python course.
I can't wait to get started!