Right now it supports Dropbox, Box, and Google drive, with SkyDrive coming soon.
We'll take a look into evernote - Hadn't thought about that before.
What would Evernote support look like? Do you want to access your notes, or are you more interested in attachments?
Seeing notes as files (plain text or whatever they provide). Not sure about attachments, it could be abstracted in various ways. Then there are Skitch files, that have become part of Evernote.