Thanks for the tips guys; I figured it would be a case of several possibilities. Tappet noise from cruddy lifters was the simplest guess - I do know that they can go 'off' after prolonged periods of sitting, and so even at low mileage, it's possible to have it making a bit of a racket. Interesting thoughts on the other ideas.

I'm a little concerned about GM taking care of it, too, but they did mention that they'd send it to the local Chrysler dealer if they couldn't figure it out... heck, maybe I should tell them to take it to the local Mercedes dealer, at this rate.

I'll add a link to a video I took of the noise (at the bottom of my post); I took the video with my iPhone 4, at operating temperature (it had been driving for a couple of hours straight).

As to why I went with the non-SRT-6, it came down to the simple fact that this car had about 1/6th the mileage, and as I was looking for a daily driver, and one that would preferably last for many years to come, I wanted to have as 'new' a car as possible. This car has 21,000 KM's, the other had nearly 120,000KMS. For all intents and purposes, this car that I bought is indeed in 'almost new' condition (it even smells new, inside), despite these relatively minor issues.

Link to my cruddy iphone video (the ticking is fairly evident... from the sound, I almost want to guess exhaust manifold, now!): IMG 05031 - YouTube