Early rumors put the Lynnfield chips and the accompanying P55 chipset launching at different times. Now it would seem that several Taiwan hardware manufacturers are saying that both will be launched on September 1st.
This makes much more sense as the P55 chipset utilizes a new socket for Lynnfield CPUs and it wouldn't have done much good to have one without the other. Now the whole platform wll be launching together, negating this issue.
At the same time, the P45 chipset will be getting the axe. Those with LGA 775 processors will still have options through 2010 however, as the P43 and G41 chipsets will stay in production.