I have some more details on the upcoming Nikon announcement. There will be two dates: August 17th, 2010 will be for the Coolpix models and August 19th, 2010 will be for the four new lenses and the Nikon D3100. Those dates are European time - the announcements in Europe should happen early in the morning, around 6:00 am. For the US readers this will mean that the announcements could happen around 11pm or midnight EST on August 16th and August 18th, 2010.
I seriously doubt that something else will be announced on those dates or before. There will be probably another announcement before (or during) Photokina.
I have no dates or any new info on the potential D90 and D700 replacements.
See my recap for all the details.