I'm having deja vu all over again... last winter/spring, on either DG or GardenWeb forums, a very similar conversation took place (as I recall, that person said the rush of invasives was just another facet of evolution).
Sometimes we get so caught up in the academics of an issue that we ignore the practical side of it (same could be true in reverse, I guess). We can get all tied up in knots about whether a plant is truly invasive, about *why* plants are invasive, and whether the word "invasive" is even the correct terminology. None of that addresses the issue of non-native water plants are choking the waterways, or kudzu across open fields and jumping from tree to telephone pole to next tree with abandon.
Responsible gardeners need to recognize and admit that not every species of plant is appropriate for their location. The resources that Chris provided are good starting points. There are lots of things I would like to plant that either remind me of my original home or just look beautiful, but I choose to research before planting, and avoid those listed as invasive for my state/area. I'm lucky in that I don't have to battle kudzu in my own yard, but it's all around my area and is a never ending battle down here.
As humans, we're never going to live in an area where humans have not interfered with an ecosystem. If using the term "invasive" is what's needed to help people understand "OMG DON"T PLANT THAT HERE!" then it's the correct term, even if it's technically incorrect.
Just my 2cents -- feel free to disregard.