Got a report from large camera retailer: in their internal documentation the Nikon D60 was labeled with a replacement due in "early August". This information match the previously reported Nikon announcements on July 30th and August 4th. Nikon D60 has already been discontinued and a D4000 is expected as a possible replacement (a strip-down version of the D5000, maybe without video and swivel display).
The combo D300s + D4000 + new lenses is the most probable scenario for the two upcoming Nikon announcements.
The other possibility is D300s + a new D3 (D3h, D3s?) but the latest rumors I received were pointing to a D3 refresh in Fall. It also doesn't make sense to schedule two different events and announce two PRO cameras - one of the event will be for PRO equipment and the other one for consumer cameras.
I don't think any point & shoot cameras will be part of this announcement - Nikon released eight p&s cameras back in February of 2009. The only possible Coolpix release is a Nikon P7000 (replacement for the Nikon P6000, which is almost a year old), but I don't think this would be the case.
At that point I don't have any reliable reports about lenses that may be released at those events.
D300s release NR probability rating: 99%
D4000 release NR probability rating: 75%
D3s/D3h release NR probability rating: 20%
Coolpixes release NR probability rating: 30%