There are few services which you can forward tracking number, and they update you when the status has changed.
UPS shows you how many days till delivery now, and you can have them remind you but it does not work too well, always delayed, but never the else I don't see it being useful as something like tripit at all
I simply keep checking that folder once in a while to see if I received what I ordered.
TripIt has an email address (plans@tripit.com) that you forward any emailed itinerary to. They process the email, figure out where you're going, etc and then put that info into your account. Granted there's are many more formats of shopping confirmation emails than there are airlines, but hopefully you'd only have to teach it a new retailer once.
But then, I don't buy that much stuff, so having to keep track of it all on a dedicated site would be overkill.
But also, I'd want the information to be accurate, and such package tracking information as is available where I live doesn't seem to be accurate.
Then there's that knowing the package has been loaded on a van doesn't tell you anything helpful. Once I had a package that was loaded on a van three days in a row.
Maybe it's a question of market segments. FedEx does operate over here, but I imagine they're more expensive than the delivery companies commonly used by UK shopping sites. If I tell you that ParcelForce and CityLink are commonly referred to as ParcelFarce and ShittyLink, that should give you a clue as to the quality of their service.