Right I should have noted this in my original post as well.
I've already performed this exercise by downloading the ALSA drivers from realtek, compiled them as well to no avail.
As I said, surprisingly, zotac z68itx-a-e uses the same audio chipset (realtek alc892) as the asrock h67mitx/ht. If the driver used is the same one and i can confirm that it is, there is something very strange that the zotac guys have done with respect to how the bios reports the realtek audio chipset's pin configuration (atleast where linux is concerned). Windows setup on both these board has no problems.
infact the jack sensing is spot on in windows.
I'll probably end up selling the board if Zotac is unwilling to do anything about it. The only reason why I am considering keeping this board (zotac) is that the same configuration of hardware runs so much cooler on the zotac (can barely hear the fan at 1200~1500rpm) where as the asrock runs hotter and hence the fan on the stock intel cooler is revving at 2700rpm.
Edit: i see what you're saying. its probably linux drivers. and given the fact that the drivers work for the alc892 on the asrock board, even the linux dev team will have problems believing me... what an uphill battle... well i've already submitted a bug report on launchpad.net...
"Look at me, I'm Dr. Zoidberg, homeowner."