Found a screenshot on the Nexus forum from someone who had finished preloading:
http://postimage.org/image/6fxm8e8d7/
Interesting to see that the voice bsa file is 1.3 GB while the Oblivion ones were 1.66 GB together, and Fallout 3's 1.72 GB. Looks like they definitely improved their compression, as I doubt we'll have less voice acting.
Also there's an update.esp (or esm, can't see) , which I assume is what they'll be using for those quick updates they promised. Better than having to download the whole 240 MB Skyrim.esm for every patch!

http://postimage.org/image/sqjynnrx3/