As of 12/14/2012 this is version 1.2.1, which includes compatibility for Jellybean 4.2 (finally!). For future releases I'll update the file link and meta info in this same blog post.
It's signed, but for your safety:
Certificate fingerprint (MD5): B2:BC:85:F9:F0:24:7B:C6:BC:2D:B3:68:77:05:B8:B6
$ shasum Screen\ Filter.apk
4eb6ab0f916a979ba1cd41e4a182e48ed5f47d05 Screen Filter.apk
$ md5sum Screen\ Filter.apk
c6e9825ad44211e9eabb1b97db5b2d50 Screen Filter.apk