Seems a bit weird and pointless considering they only managed to secure exclusivity in Europe.
All Sony Europe is doing is limiting your choices, and possibly delaying it three days (provided Atari was planning a simultaneous NA and UK release).
"A new deal between Atari and Sony Europe by which the latter will publish Ghostbusters in the PAL territories means the title will be exclusive to PlayStation platforms in Europe, Atari clarified today.
The deal won't affect the game's North American release, however. Atari will publish the title as planned on Xbox 360, Wii, PlayStation 3, PS2, PC and DS on
June 16th stateside.
Sony will publish the game on
June 19th in Europe -- on PlayStation 3 and PS2 only. According to Atari's announcement, the PSP version of Ghostbusters planned for Autumn 2009 will release worldwide."
http://www.gamasutra.com/php-bin/news_index.php?story=23503