leo72:
Both Arduino 1.0.x and 1.5 have been merged into IDE 1.5.1 ...
My attitude is, when it shows up here... http://arduino.cc/en/Main/Software ...it's official. 
I've tried to put the Tiny core inside the /hardware/arduino/avr/cores folder but it seems that it doesn't work. When I open the Tools/Boards menu I don't find the entries for the Tiny MCUs...
That's not good. I'll try to spend some time on it this weekend. Thanks for the heads-up.