Ok, my earphone seems to be screwed after flashing from UK variant to Global then back.
I'm current on 203 PR1.1 (after flashing to Global PR1.1 and upgraded to PR1.1.1 then back due to bug it's not restoring Conversations) and now the N900 no longer picks up the presence of earphone..

Playing some music with earphone plugged in but the sound still blasting out from the speakers

I'm using the Nokia earphone from the original N900 packaging.

syslog shows it's picking up the fact earphone is plugged and unplugged though

Feb 23 15:42:17 Nokia-N900-51-1 kernel: [ 851.775360] headphone (GPIO 177) is now connected
Feb 23 15:42:18 Nokia-N900-51-1 kernel: [ 853.353118] headphone (GPIO 177) is now disconnected
Feb 23 15:42:20 Nokia-N900-51-1 kernel: [ 854.587524] headphone (GPIO 177) is now connected
Feb 23 15:42:21 Nokia-N900-51-1 kernel: [ 856.376403] headphone (GPIO 177) is now disconnected
Feb 23 15:42:23 Nokia-N900-51-1 kernel: [ 857.853027] headphone (GPIO 177) is now connected
Feb 23 15:42:24 Nokia-N900-51-1 kernel: [ 858.860870] headphone (GPIO 177) is now disconnected
Feb 23 15:42:25 Nokia-N900-51-1 kernel: [ 859.884429] headphone (GPIO 177) is now connected

Anyone else experienced this?

I am also experiencing this bug. I thought I had broken my headset, but apparently others are experiencing this as well.

Same here but only with the earphones supplied by nokia all my others work .

I've created a bug earlier today, feel free to vote.

https://bugs.maemo.org/show_bug.cgi?id=9237

Those who experienced this bug, did you do exactly as I did? ie flashing to different variant firmware.

i flashed mine from 205 UK Voda to Global firmware and just now tested headphones that game with phone. no problem here

p.s i also flashed emmc