There's an easy way and a hard way to learn about the proof of Fermat's Last Theorem.
THE EASY WAY
The easy way is just to watch the videos and read popular accounts.
For many years, msri have had a video online
Google video has recently added the uktv video to the internet which is better than the msri one
Here they are: <a href="http://video.google.com.au/videoplay?docid=8269328330690408516">uktv</a> ; <a href="http://ia300112.us.archive.org/2/items/fermats_last_theorem/fermats_last_theorem_256kb.mp4">msri</a>
If you want a higher quality version of the uktv one, several torrents of it are available online.
Note that the uktv (bbc/wgbh) one has Eve Matheson narrating and is slightly out-of-sync. There also exists an identical nova version (pbs) narrated by Stacy Keach instead, called "The Proof", but thus far I don't think the nova one is online. This one is better (in-sync). I've got both versions. Although the nova version isn't online, nevertheless the transcript for it is:
http://www.pbs.org/wgbh/nova/transcripts/2414proof.html and nova has made a whole website for it at
http://www.pbs.org/wgbh/nova/proof/
Even though the uktv one is better than the msri one, I still think it is good to watch them both.
There are other videos from the ams which are not online yet and are also good to watch, but are more technical:
"Modular Elliptic Curves and Fermat's Last Theorem." Kenneth Ribet; August 1993. American Mathematical Society, 1993. (Available at
http://www.ams.org/bookstore?fn=20&arg1=videos&item=DVD-89)
"Fermat's Last Theorem." Barry Mazur; AMS-CMS-MAA Joint Invited Address, August 1993. American Mathematical Society, 1995. (Available at
http://www.ams.org/bookstore?fn=20&arg1=videos&item=VIDEO-97)
There also is a more theatrical video called
Fermat's Last Tango available at
http://www.claymath.org/publications/Fermats_Last_Tango
Popular accounts:
Singh, S., Fermat's Last Theorem, Fourth Estate, 2002
Azcel, A. D., Fermat's Last Theorem: Unlocking the Secret of an Ancient Mathematical Problem, Thunder's Mouth Press, 2007
Ribenboim, P., Fermat's Last Theorem for Amateurs, Springer, 1999 (note there is a 2nd edition in 2000)
Mozzochi, C. J., The Fermat Diary, AMS, 2000
Mozzochi, C. J., The Fermat Proof, Trafford Publishing, 2006
THE HARD WAY
The easy way raises awareness with the public but as Andrew Wiles himself has said there is simply no substitute for hard work. And the hard way is as follows:
If you only want the mathematics needed to cover Wiles' proof, then you should read his proof (which I mentioned in <a href="http://community.boredofstudies.org/2436198/post-9.html">this post</a>) and references contained therein. Also, since then a textbook has been written to facilitate this process. It was originally written in French, but was soon translated into English:
Hellegouarch, Y., Invitation to the Mathematics of Fermat-Wiles, Academic Press, 2001 (English translation by Leila Schneps, 2002)
Unlike most books on the subject this one contains a large number of exercises to assist you to not only read it, but more importantly, to actually
learn it.
Nevertheless you will need to read more widely if you want a firmer grasp of the mathematics used in Wiles' proof.
A good start are the references Ribet mentions at the end of his 1993 video but does not give details for. Here are those details:
Lang, S. and Rubin, K., Cyclotomic Fields I-II, Springer, 1989.
Silverman, J. H. and Tate, J. T., Rational Points on Elliptic Curves, Springer, 1992 (note also that there is 2nd edition in 1994)
Silverman, J. H., The Arithmetic of Elliptic Curves, Springer, 1986 (note there is a 2nd edition in 1994)
Cornell, G. and Silverman, J. H., Arithmetic Geometry, Springer-Verlag, 1986 (note there is a 2nd edition in 1998)
Knapp, A. W., Elliptic Curves, Princeton University Press, 1992.
Hearst III, W. R. and Ribet, K. A., Book Review for Rational Points on Elliptic Curves by Joseph H. Silverman and John T. Tate.,
AMS Bull.,
Vol. 30 No. 2, April 1994, pp 248-252.
In 1995 a conference was held on August 9-18 at Boston University to cover all the maths Wiles used and the notes were published in
Cornell, G., Silverman, J. H., Stevens, G, Modular Forms and Fermat's Last Theorem, Springer, 1997 (note there is a 3rd edition in 2000)
This is the definitive book on the issue. But it's best to consult the other references I've mentioned first.