No microphone...
And a reboot do not solve it , i didn't set up the radio app...

sigh....

I'm in the same boat. Got my N900 delivered on Dec 10th, got it activated on the 11th. The mic doesn't work, and hasn't worked since moment one. I never installed the FM radio app.

Try reflashing it. Heard that it may solve the problem with the mic. But I really hope mine is not one of those N900 that had Mic, dead pixel problem.

I reflashed the eMMC and the firmware. Still no help with the internal mic problem.

Well, I have one dead pixel on the lower left side. Got a replacement device but I haven't received it yet. The rest was fine. Battery was great. I had no reboots and no mic problems.

send it back to Nokia for warranty

Quick update. Sent my faulty N900 back to Nokia on 04/12 (mic was not working) and they have sent me out a replacement out today (15/12) and hopefully I will receive it in the morning. More hopefully it will be working.

Just for arbitrary information there's approx 577,000 of a difference between the previous and the new IMEI's.

4th? Blimey- I was hoping they'd be quicker than that. Sent mine back this morning. I was hoping to get it back for Chriastmas.

Saying that the 4th was on a Friday, so that shaves a few days off. So you could possibly get it before Christmas, but then again ......

As you know, I too have an N900 with a non-functioning microphone. Reflashing the firmware did nothing to resolve the problem. I talked to Nokia today, and they refuse to repair or replace it; they say I have to go back to the retailer. Amazon won't replace it either. They will refund my money, but they will not ship a new device. The price has gone up significantly since I placed my pre-order, so no matter what, I'm going to incur additional out-of-pocket costs to get this factory defect corrected, which is total BS if you ask me.