Sure, Porsche developed the PDK (dual-clutch sequential) and used it in the 80's on the Group C 956/962 race cars, then shortly after Audi started to use it the as well in race cars. But to give some credit to Audi, they are the first ones to develop it for street cars.
I will be pleased if the DSG is offered by Porsche, even though I won't be getting one myself if available, the more options for our fellow P-car owners get the better. If it delivers what is promised, a 6 or 7 speed double clutch sequential will be much faster in shifting than BMW, Ferrari and such single clutch sequentials and manual gearboxes, it will weight similarly to a manual unlike the slush-boxes, it will deliver faster acceleration times than any other gerabox incl. manuals or single-clutch sequentials, it will be more confortable and smooth than the single clutch sequentials, and it will also facilitate faster lap times at the track by diverting less concetration from the driver than a manual.
So why won't I personally get it?... because it takes away part of the pleasure of the driving experience of sportcars for me. Bypassing the shifting is diluting the experience, makes it less challenging, less driver intervention, less things going on in the whole process, less skill that is asked from you, detatches you from a very important part of the car, etc. And what are sportcars cars all about? to some like me it boils down ultimately to "driving" and "fun and pleasure at the wheel" even more than fractions of a second at the track or in a 0-60. I won't jeopardize or trade off a bit of the driving experience for a fraction of better performance. If they invent an electronic mechanism that will steer the car for you around the track with the skill of shummi would you I that too?
The only time when I happily trade performance or driving feel/experience is when safety is involved such as ABS, PSM, heavier chasis if better crash safety, AWD in some cases, etc.
But I see it as a GREAT option for people who have stop and go commutes everyday and can't really take advantages of the manual enough to outweight the confort of the DSG, for people who simply don't like, can't use well or never bothered with manual shift, for guys who's wife will also drive it but can't drive a manual, for people with back realated injuries, for people who want the car exclusively for performance, etc. So its a matter of needs and personal situation, the best thing is to be able to choose so I hope it comes out soon for those that want it.