Hey, i am Daniel from Germany, so please excuse if i don't write english that well.
A few days ago, i bought a Canon 500d (Rebel T1i /Kiss X3). I decided to do that instead of buying the D90, because the Image-Quality seems not to differ very much from the D90 or D5000, but the 500d did HD (1280x720) Video at 30 fps instead of 24fps.
Well, then i realized, that it will never be easy to make a 30 fps Video to a constant floating 25 fps Video, which we need here in Germany for PAL Output at the most TV's right now. Also, the 24p (24 fps) seems to be the standard format for cinema.
Then there were some other upcoming issues, like the slightly better performance of the dynamic range and noise of the D90 compared to the Canon eos 500d.
So i went back to the store and gave the 500d back to get a D90.
All right, so i tried it. And i have to say, it is a very nice photo-camera and i think, in photo(Main!)-mode it is better than the 500d. Now i will not write much about the pros and cons between the two cameras, because the topic is the video mode.
So i did some Videos at daylight. Everything was fine and i get was i was expecting, since i watched so many Videos on youtube (in HD !).
Then the sun descents, the lights were switched on and the waves began to travel. Flicker on my Videos!.
All the Lights in the City are pulsing with the Frequency of the alternating current of the powernetwork. And here in Europe, we have 50Hz, so 100 times a second, because the intensity of the Lightbulb is maximum at the negative and positive maximum of the current. I think i am writing to much what you already know.
So, this problem is general for a roling shutter, which the D90 uses, because it has a CMOS Sensor. The wobble effect has the same root, of course.
I can live with the wobble-effect, but the Flicker is very ugly. I would go so far, that i think, in this condition, the D90 is not suitable for indoor and night, because then i have flicker 80% of the time. (of course i know the workaround, were i have to play with AE-L and EV and ">"+"up" or "down" and hopefully get low ISO...
But As i said, i have seen much Videos on the internet and i really think, the new good quality of such consumer cameras are a opportunity for a new phaenomenon, were more and more non proffessionals are publishing nice short films or documentarys. But non of them wants a camera, were you don't even can shoot indoors or at night.
So since we know, that a manual exposure control of the D90 will give the user the power to make the Flicker completely (or at least almost) go away in alomst every situation, i would be very surprized, if Nikon will not present a new Firmware or solution for this problem in the very near future.
Since i don't know, when such a Solution will come, i will go back to the store and get the EOS 500D back.
Good Luck for all of you !