[emory]

a) You're in violation of your agreement with Apple by discussing Mountain Lion in a non-Apple channel.

b) You haven't set Mail.app as your default mailer for every URL handler that Sparrow has. Sparrow (stupidly) has several and you can't get at them without help. Install the "Default Apps" preference pane to change your helpers for the URLs in OmniFocus.

When in doubt about pre-release software, email support ninjas instead of posting a message here.