Thanks bro for the answer,it makes sense,but we are so unfortunate to have a flagship device of World's leading smartphone maker with out a builtin Compass.
Actually, Nokia never classified the N900 as a flagship device. All indications from their marketing are that the N900 be treated as a dev environment for enthusiasts. We expect this to change with the N9 running Meego.
The last Nokia flagship device was the N97. The N97 DID have a magnetometer.
As discussed elsewhere on the forum there are two magnets (one for the back stand/cover removal detection, one for the keyboard slide out detection) that might interfere with a magnetometer afaik.
Today Samu Onkalo from Nokia posted drivers to Linux kernel mailing list for ak8974 / ami305 3-axis magnetometer chip. Maybe that is a clue what hardware could be in a future Meego device?