I haven't upgraded to Tiger yet because it won't arrive from Amazon until tomorrow. But today Software Update on my Panther-running PowerBook informed me that Quicktime 7 was available.
Given that the Quicktime 7 upgrade is available for Panther, it isn't really accurate to say that Quicktime 7 is a feature of Tiger. It just happened to come out at the same time and so is bundled with it.
I wonder if any other so-called Tiger features will be available as free Software Updates for Panther users. I'm guessing Safari 2.0 or Mail might be another contender. Maybe even iChat AV.
There may be broken links to media on this page. I'm still in the process of migrating them over.