This isn't the first time a Mazdaspeed 6 was rear-ended and photos were posted on the forum, but, to me, it is a tragedy every time. The Mazda 6 holds up quite well with these sorts of collisions but any kind of frame damage or too much force into the transmission/motor area can easily total this beautiful car. I wish you luck, and please share the details of this situation if you wish.
It really sucks when you have a brand new car that's hit. If there is significant damage, you may also want to inquire about something called Diminished Value. Since your car was in an accident (assuming it can be repaired), it will lower the value somewhat of the car. Speak with the person's insurance who ran into you about it, or maybe seek some legal advice if you can about it.
Good luck with the repairs and getting everything straightened out.
LapisLazuli6 is right, be sure to collect the check for depreciation. i had an incident last year with my traded in 2004 M6s when a gravel truck lost part of its load and caused $3,800 damage. after all the repairs i got an additional check for depreciated; not enough, but something.