It is correct as pinkunicorn says. There is no complete list available. That's why we created http://project-gc.com/Tools/SouvenirList
, which is a list of souvenirs we know of. Made from data of which souvenirs users has achieved.
Also as mentioned, there is no grouping at Geocaching.com, and maintaining groups on new souvenirs at Project-GC will mostly make it weird. I am sure that Groundspeak has some thoughts about how Souvenirs will develop in the future.