I am in Florida and was focused solely on 2009s as that was where the most 911 incentive money is. I wound up buying one out of Tenesse since it was on the lot with the build I wanted and the deal was $10K under invoice. I have been told by 3 dealers that the Porshe money is now only $8K.
The most aggressive deal I found was at Porsche of Orlando and they were willing to sell a lightly optioned PDK car for just below invoice. Brumos offered 14K off MSRP. Champion offerred 16K off MSRP. I also think I could have gotten $8K under invoice at the dealer in Dallas, where they have a totally bare bones cabriolet.
Obviously it all depends on the build and the dealers level of motivation. I spent hours on line and just sent e-mails to dealers that had cars I wanted asking them to sell it at $10K under invoice saying I knew there was great porsche trunk money out there.
You have to pay cash or bring your own financing as the trunk money is in lieu of other incentives.