Dropbox just implemented the ability to add a pin or use your thumb to access it, which I'm super happy about as there are some files I'd prefer people not to see by accident (e.g. finances). I would love it if Evernote implemented something as sweet and simple as that, accepting it's not encrypted.
I appreciate there is a list of priorities, however it's surprising that this hasn't been addressed as yet as I would imagine a significant proportion of the user base use Evernote for business and personal notes which are sensitive in nature.
Wholly agree with mkg, when he says "Again, not looking for any true security but rather protection from the most casual / opportunistic peeking which solves 99.9%+ of occurrences we care about. "