trevorseward on "[Plugin: Jetpack by WordPress.com] JetPack throwing CAPTCHA error when attempting to post a comment"

Further information, I'm getting HTTP 500 errors when a user attempts to post a comment:

[18/Jun/2013:16:53:17 +0000] "POST /wp-comments-post.php?for=jetpack HTTP/1.1" 500 4184 "http://jetpack.wordpress.com/jetpack-comment/" "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537
.36 (KHTML, like Gecko) Chrome/27.0.1453.110 Safari/537.36"