Starting January 2009 all new games will be required by Sony to have Trophy support. This is according to VideoGamer.com who received confirmation from a SCEE representative. We've emailed SCEE to check that this is true. Considering the number of games that released this year with Trophy support (a great deal more than we expected, that's for sure), we'd be surprised to see any games release without the feature starting, well, now to be honest. Hopefully the idea of a "Trophy patch" will soon be a thing of the past.
[UPDATE] SCEE has confirmed to us that, yes, all games released from 1st January 2009 will have Trophy support out of the box.