I can confirm that PSD is currently broken in the Google Docs Viewer tool, which my plugin embeds. PSDs continue to display correctly in the viewer if opened from Gmail or Google Docs, so this is an issue with the standalone code.
I’m already seeking a solution to this problem with Office XML formats and have added this to my request, but so far nobody at Google cares to support their product. 🙁 Hopefully I will be able to give you an answer soon.
Possible temporary solution: output the PSD to PDF first.