Ahem...
For gamecube, I don't kno wof any functional chips...but you may want to try
this as far as PS2, there's several options. The most obvious is a mod chip, but you have to know how to solder or pay someone an obscene amount of $$$ to install it for you. There are solderless options now as well, including a boot disc of some sort. It's like $20, and it works. Check out
www.chipzone.comAs far as GT4. Don't worry...it's one of sony's most popular titles, it would be foolish for them not to bring it here. What you heard isn't true anyway...i've already seen ads for GT4 around. Also, when you're buying import games, be aware that alot of stuff is probably going ot be in japanese!! Might not sound like a big dealbt when you can't read what's on the screen it can suck big time.
Unless you're looking ot get into bootleg games (which then we should talk further) don't bother, just wait for the US version.