My N900 display has started to make noise when pushing it either with finger or with stylus.

The sound (and feel of screen somehow being loose - not sideways, but depth-vise) started first from the left top corner and the status bar where profile, connections, alarms and availability etc. are set. It did the same soon after from the bottom of the screen and now the whole screen does cracking sounds although not every time that I push an item on the screen.

Has anyone else had the same problem? So far, the display works fine though. No issues of responsiveness or clarity or anything. Would this be ok for change by Nokia under the international guarantee?

Can't understand what you mean by "pushing it". You shouldn't need to "push it". I find I get by with just a touch of the thumbnail or fingernail is enough to activate anything.

Anyway, to the problem. There were some issues with some screens (pre PR1.2) where the top left and the extreme right of the screen were were a bit dull in the sensitivity dept, thus needing a bit of extra pressure, but I'm guessing you're already running PR1.2.
Another problem that was displayed by some screens was that the metal bezel actually warped/twisted and worked loose, I'm not sure what the fix was in this case, but to check for this, slide open the screen and check the gap between the bezel and screen back-plate. See if the gap is the same all the way around.

No harm in contacting Nokia themselves for advice though.

I had the same problem on the status bar. Luckily lasted only a day and then just went away. It produced a physical click each time i touched it. Horrible user experience for a device this pricey.

I run PR1.2 since the day it arrived. I've never had real responsiveness issues. Nor do I really push the screen as I would push a keyboard.

However, a gentle touch which goes just a tad bit more than what you describe (hardly touching anything on the screen at all) is enough to create the sound, just as afaq mentioned. The click isn't there every time. However, the whole top part of the phone makes these clicks and rattles every now and then, and I am wondering if the frame would have got loose. Given that the phone has never dropped even on a carpet, this is a bit surprising.

I will probably take it to Nokia as you suggest. Since there's a guarantee, I am not going to try to open anything myself.

i also had the problem, it has something to do with teh metal case around the screen makes a clicking noise when you press the screen on the edges. its like the display is not on its place.

If it is a physical design issue, then I guess I will have to live with it - or do you imply that it can be fixed by Nokia service?

Some searching revealed this thread: http://talk.maemo.org/showthread.php?t=56730&page=2

It seems the issue could be just a bit of dirt. Cleaning under the frame might solve your issue. Look at that thread please.