Hi Jake
My company’s product - SharePoint Reminder - may do what you want.
For example if you had an expenses doc library, and assuming you are
'grabbing' the appropriate fields from your InfoPath form into library
columns you could setup the following Reminders. Keep in mind that this is
only one example - its pretty flexible.
1) When a expenses form is submitted it emails the user who is listed as
that persons 'supervisor' alerting them that they need to approve an expenses
claim.
2) When the supervisor approves the claim it could email an accounts/admin
user and cc the person who filed the claim - letting them know it has been
approved and is ready for payment.
Check it out and if you have any questions then drop me an email.
http://www.pentalogic.net/SharePointReminder
Cheers...Ryan