A NR reader emailed Nikon a couple of weeks ago to ask them about firmware updates for the Nikon D90. This is the answer he got:
There are no FW-update to the D90 yet.
We have been told that there will be several FW-updates to our cameras before Christmas.
But we don't know to which camera models or what have been changed.
You must wait and see what happens.
Nikon Europe Support