I just checked out of my St. Regis Rome jr. suite an hour ago, and butler service includes:
* morning coffee / tea service
* pressing of two shirts upon arrival
* luggage packing and unpacking
* shoe shines
There were a few other services mentioned in the literature, but were probably not worth remembering.
I used the coffee / tea service, the shoe shine, and shirt-pressing (but was charged 20 EUR for this, and will send a note to the hotel asking for a refund).