The games in Ubuntu's standard installation are there because they're free as beer, and I guess a Solitaire or Sudoku doesn't take much space on the CD.
Originally Posted by BlackStar
I doubt games in the Humble Indie Bundle qualify.
Now if you mean having them in the standard repositories available out-of-the-box through the software center (if I remember correctly Mark Shuttleworth mentioned offering proprietary apps there too in the longer run), then yes sure.
Now Steam is on its way too, though I don't know about their licensing model requirements. If it's any indication, World of Goo is already available from the MacOS port, and it's the only game from the bundle that won't offer the source code...