The N900 screen has haptic feedback, but is it supposed to provide a vibration on all screen touches, or is this selectively controlled by the applications? I do have enabled Settings > Display > Touch screen vibration enabled and I do get a clear vibration response when I "End" a call in the Phone app. But that is about the only place I'm getting haptic feedback. Is this the design, or is this a bug, or is my unit defective?

It is not a true haptic screen in the N900. All it does is using the vibrate hardware regardless of where you touch the screen.

A real haptic screen lets you feel a feedback at the place of the touch.

I turned off this feature the first day I got the N900. It was so annoying.

It's there but the default setting is quite weak and is more of a jolt / jerk.
The feedback is for ALL screen touches and not just for the phone.

You can change how it feels by doing the steps I mentioned below:
http://talk.maemo.org/showthread.php?t=39320

You can tweak it to make it feel like 'nearly' any phone/touch device.

OK, so is it possible that the "End" button in the Phone app is also triggering the phone vibrator device? I certainly do not seem to be getting any physical sensation by touching the screen at other times.

hmm. it should. It does with 2 x N900's that I got access to.
It's a very very short jolt however. Some people hardly feel it.
(hence if you change mce.ini, it becomes more noticeable)

Better to leave it off...it's a huge power drain

Yeah, I have it off also. =P

Any additional info, please, regarding 'huge'? I understand it uses battery, but I am curious about 'how much'?

TIA,

bun

I get quite the uptime with my N900, as in full BT and wifi, sometimes tracking wifi for hours (I'm responsible for it). Also, demo the device, video, net, mail, all that I need and I still have battery left when I get home.

Push the display from 2 blobs to 4 and get a flat before I get home. Thus, screen is a major drain. I didn't notice a diff with haptic.

Also, most of the times it's just a very light jolt, like someone taps the device. When on a hard surface, it feels like someone is tapping the table, not like it buzzes/hums.

Add these up and I have maybe a minute or two of continuous hum. Considering a missed cal is 30-60 seconds humming plus light and song, I'm guessing haptic is minor?

to enable it you also have to enable the notifications!