Downloaded it twice and get the exact same error. Deleted and removed from trash the first time.
Edit Reboot your machine. That worked for me. I can now install fine with the same 'corrupt' file I had before.
I posted my md5's of the internal .dmg's from the download there. They're different from the two unsuccessful downloads but I suspect that's just App Store watermarking because they differ in so many places. Maybe someone here on HN knows the real story though.
It's odd that I had two failed downloads in a row... Either an app store bug or this MBP is maybe having memory issues or something. It's odd because I haven't had any issues like that before, and I tax it quite a bit.
Or maybe this was just Apple's way of making me rationalize a MacBook Air purchase :-)