it is a bit on the low side for me as well, let's just hope it can be adjusted with a firmware like the 6300c was

Jidi is right, make sure the volume is set to max, I was quite annoyed until I realized that

a) volume is at 50% from box
b) volume buttons swap when you rotate phone
c) volume is per-app and global, nice but tricky.

All that said, I expected it to bake my ears bleed since the speaker is quite nice. Earpiece is average, sounds almost identical to my old N80 and 7610 (and every other Nokia I had).

At least on N80 I could set it to speaker and hold the phone sideways. I look like an idiot but it's guaranteed to deliver. N900 can't really be used like that.

While on a call, I set volume on the ear piece and speakers to "max", and still felt it was too low for each respective method. Conversely, media playback volume is more than ample. It seems almost as if the 80-90% of max on the speaker is what the max of the earpiece "should be".

Is this something that can be adjusted "by the community" pre-official update (if Nokia is even aware of this issue/request)?

Has anyone tried to make programming changes to raise "call volume"? Or make a "phone volume" applet? I'm noticing call volume are low not only thru cell, but Skype, and my SIP clients.

A very objective test comes from recording the phone calls (e.g. using the recall widget). It is clear in my case the difference in volume between my voice (recorded by the mic) and that of the other speaker. There is a HUGE difference. That could not be due to dirt or plastic covering. I think it's a bug.

This is definately an issue that needs addressing. I can't use my N900 as a phone unless using a bluetooth headset or the provided earphones. Without these aids I need to be in a very quiet room to hear the caller, despite having the volume turn to full.
If I switch back to my k800i or any other phone I have managed to test with everything is loud and clear. As a result I now use the N900 purely as an internet tablet and use the old phone for calls.
Also I have had several people test the phone to see if they have difficulty and they all had the same problems. How this got to market with such a flaw is astounding.

I did this mod to my earpiece and it has helped a good deal:

http://talk.maemo.org/showthread.php?t=46581

Dude, I made the same mistake. Thought I had installed something strange, but then I had misfitted my screen protector so that it covered the ear speaker. So, good thing I found this thread!