To add to my +1 -- I would love to see this available in various forms -- recurring Milestones, Tickets, or Tasks.
Ideally, I'd love to see this tied together with a Ticket Template feature -- recurring tickets from a template would be ideal.
For an example, see Freshbooks' - Recurring Profiles www.freshbooks.com
I'd like to be able to name those Recurring Tickets inside the project but have them pull from a global Ticket Template repository -- or at least a per project repository that you could copy other Ticket Templates into....
And to have the choice of keeping assignments or re-assigning them when you create the new Recurring Profile. i.e. you might have the same people always assigned to specific tasks (re: webmaintenance) or you might want to assign people per project.
To combine this with a template feature would be ideal. Being able to assign people in templates would be great, and the template assignments should then be omitted from assignment filter, calendar, etc.