The endurance races sure are slow and boring... unless it's actually competitive. Thanks god there's the B-Spec mode in this game. I can race and go to school at the same time!
About the online thing... Polyphony plans on releasing an expansion disk for online play, or possibly an online download of some sort using an expansion disk. But, you can also play online right now, too. PSM (the magazine) demonstated how you can play GT4 online using the LAN feature. I forgot the name of the program, but there's some sort of online program that you can download. It has a bunch of buddy lists, chatrooms, clans, etc. So, simply take a router, hook you PS2 into it... and the program that you've downloaded over the net will make the game think that the internet is just one big LAN connection. If you want a detailed description of how to do this, PM, email, or IM me (If I'm even on).