Instead, Lynnfield will span Core i5 and Core i7 brands and the choice of brand will vary between features (like HyperThreading) and processor performance.
http://www.bit-tech.net/news/hardware/2009/06/17/intel-explains-future-core-i7-i5-i3-brandin/1
http://www.trustedreviews.com/cpu-memory/news/2009/06/17/Intel-Details-CPU-Naming-Plans/p1