Yes, any major update would cause massive order delays and you won't get it for probably 3+ weeks after availability (which is not always the same time as announcement).
However, the other thing to think about is that waiting for at least an official Tiger release date (if not the actual release) will allow you to get Tiger either for free or for a minor upgrade fee. Right now, you'll be looking at $129 upgrade (proabably). I think Tiger will be worth the upgrade, but you can decide that for yourself. Of course, $129 may well be worth not having to deal with Windows headaches for the next few months.