Apple seems to have equipped iTunes 8 to detect and prevent the Pwnage exploit, iTunes 8 will now flash the error below if you try to load an Pwned IPSW file with an unPwned device preventing the exploit to suceed.

But, the iPhone Dev Team seems to have already figured the way out by patching the iTunes 8 itself,
In an blog post iPhone Dev Team said:

The nice thing about iTunes decisions is that we can provide you with patches to counter them. We have one such patch already for Mac iTunes 8 for iPod touch. We’ll be working out the full suite of patches for all the combinations over the next week.