Intel's upcoming flagship client processor, codenamed Gulftown will get the higher Core i9 marker. This 6-core chip will have every performance enhancing feature in the book available, including a total thread count of 12, and a 50% increase in L3 cache over Bloomfield, at 12 MB. This chip will retain compatibility with existing LGA-1366 socket, and X58 chipset, and will be available in Q1 2010.
Intel differentiate the processors in series of markers such as "i3", "i5", and "i7" on the merit of performance and features they offer.
see this image for better understanding.