Blu-Ray, Bluetooth, A HDD, Standard CF Card Slots (and other memory forms), Linux being installable from the get go. Hackers are very resourcefull and cunning, if theres a little hole in any of those things that allows for the system to be compromised it would be exploited to no end.
I could see Sony going the route of the PSP though and having the actual Firmware of the PS3 being updated to strenghthen security measure. All in all though, the openess that Sony has expressed that the PS3 will be will make it more vulnerable than the Xbox360.
The only reason the 360 would get cracked quicker than the PS3 is because their are people in this world that truely hate Microsoft as a Company. Thats motivation right there.