If cost is not an issue one can run standby servers in multiple locations and have backups to all of them. Just as MX records allow for multiple inbound servers one can have multiple outbound servers as well. Park a few unused or vanity domains on them and have cronjobs send automated emails to yourself. I reply to those emails so the likes of Gmail see interaction between them. With time all IP addresses get good reputation.
An IP laundering service certainly sounds like a potential startup opportunity. Certainly I'd have paid for a proven good IP in the past before I developed my current solution.
...as disconnected from "email marketing services" as possible, please, because IME gmail is wise to those and files email associated with them directly in the trash regardless of all other concerns.
I suspect the reason SES is an exception is because it is very widely used for things like e-tickets, transaction confirmations and so on, and also goes to a nonzero amount of trouble to dissuade marketers rather than having them as the main customers.
