Hi Andy,
The dimensions are different between the iPod touch and iPhone, which makes me think that both devices wouldn't work on the same dock.
But, if this is an iPhone dock, and you're wondering if both products can work with it, you might find that it does work, except that the iPod touch is a bit too small for the dock's size, if it was meant for an iPhone.
If this is an iPod Touch's dock, on the other hand, that you're dealing with, then I would tend to say that no, it won't work for you if there's no extra space in the dock for the iPhone's slight more thickness to fit into it.
So, I'd say it probably depends on the dock you're using, although, regardless, both possibilities might not work, of course. Is this a dock for the iPod touch dock, or iPhone?
-Kylene