Mines is a 2005 (55 plate) manual with 36K, well maintained and never thrashed. Love the car but the engine has always been slightly tappety for a minute or two after start-up from cold, though probably more noticeably now compared to when it was new. I asked my Chrysler dealer to look at this when it was in for a service recently and they said their oil change had made it less noisy (they kept it overnight to check on start up the next morning). I didn't notice much difference and to be honest I think its just a fact of life/occassional issue with the MB 3.2 unit. Once warmed up after a few minutes the engine idles quietly and smoothly, and performs great.
Having said all that I seem to recall one or two members in the States having their lifters etc replaced under warranty, given enough persistence! Might be worth a try if the problem is severe. If mines gets worse I will ask them to look at it again whilst my warranty is still in place.
My main concern at present is a very faint whiff of burning oil now and again, which I hope isn't a leaking gasket.....!