You can run almost all software, emus, homebrew and stuff on 3.55, only the Cobra USB dongle supports 3.41 so far, but they are working on it to get it running under 3.55.

Latest games need 3.6+, although sometimes a patch is released to get them running under 3.55, but the very new ones still will need 3.6+. Most of them games patches contained 3.55 keys, so they were able to compile a patch for the game, but that changed some days ago, and there won't be 3.55 updates for games anymore. Not every 3.6+ game has official patch with 3.55 or earlier SDK compiled executable.