As an ISV and distributor of a complex managed package, with administrator accounts at various customer orgs, I would like administrators to receive a notification email when a critical update becomes available to an org, so that we can properly vet the update before advising our customers to apply it before the expiration.
As an ISV, it's very important that we get in front of the updates, and act proactively, rather than react to our customer's informing us that an update became available.
A related idea would be to post all of the Critical Updates to the partner portal, and provide email notifications to all of the ISVs with partner accounts, so that we know to review our customer orgs.
As it stands, the update alerts are only shown when an administrator navigates to the Setup menu. Rather than "stumble upon" We would prefer upfront notification. The purpose of Critical Updates is to allow us an opportunity to vet the update first, but without email notifications, we do not always learn of the update right away.
As a note, when Winter'14 was first released, with regard to Critical Update notifications, online help indicated
"Salesforce lists them in Setup at Critical Updates, sends a notification email to administrators, and displays a message when administrators go to Setup."
Since I'm have admin accounts on several customer orgs, and have never received such an update, I checked with support (#09851611), which determined that online help is incorrect and will be updated. (Though, I wish it were not incorrect!)