I'm using Realtek ALC892 with a fresh ubuntu 11.04 natty and I have the same problem but I think it may be because my chipset is not supported. 
I'm using Gigabyte GA--890 GPA-UD3H AMD 890GX motherboard.
lspci -v
00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA) (rev 40)
        Subsystem: Giga-byte Technology Device a102
        Flags: bus master, slow devsel, latency 32, IRQ 7
        Memory at fe024000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: <access denied>
        Kernel modules: snd-hda-intel

The exact chipset is SB850 and according to http://www.alsa-project.org/main/index.php/Matrix:Vendor-ATI it is supported only until SB400
I can't find SB850 in ALSA-Configuration.txt either (max is SB450)

I've tried #3 it didn't change anything. 
I've tried installing the high definition audio codec from http://www.realtek.com.tw/downloads/downloadsview.aspx?langid=1&pfid=24&level=4&conn=3&downtypeid=3 (LinuxPkg_5.16rc14.tar.bz2) but still not working. 
 This actually removed everything that was in hardware, input and output in the audio configuration panel: I have now only the "dummy output"

I'm not sure if the install is OK because it ends strangely: 
/sbin/depmod -a 2.6.38-8-generic 
cat WARNING

WARNING!!! The mixer channels for the ALSA driver are muted by default!!!
**************************************************************************
You would use some ALSA or OSS mixer to set the appropriate volume.

Creating mixer?...done.
Creating sequencer...done.
Creating midi0?...done.
Creating dsp?...done.
Creating audio?...done.
Creating sndstat...done.
Creating music...done.
Creating dmmidi?...done.
Creating dmfm?...done.
Creating amixer?...done.
Creating adsp?...done.
Creating amidi?...done.
Creating admmidi?...done.
rm: cannot remove `/dev/snd': Is a directory
Creating snd/control?...done.
Creating snd/seq...done.
Creating snd/timer...done.
Creating snd/hw??...done.
Creating snd/midi??...done.
Creating snd/pcm??p...done.
Creating snd/pcm??c...done.
Creating aload?...done.
Creating aloadSEQ...done.
Remove Folder.....
./install: 48: alsaconf: not found



Ater rebooting if i try to access the alsa mixer:
alsamixer
cannot open mixer: No such file or directory


modinfo soundcore
filename:       /lib/modules/2.6.38-8-generic/kernel/sound/soundcore.ko
license:        GPL
author:         Alan Cox
description:    Core sound module
srcversion:     982D4ED4F640D0B9C43B130
depends:        
vermagic:       2.6.38-8-generic SMP mod_unload modversions 

lspci -nnvv
01:05.1 Audio device [0403]: ATI Technologies Inc RS880 Audio Device [Radeon HD 4200] [1002:970f]
	Subsystem: Giga-byte Technology Device [1458:960f]
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 4 bytes
	Interrupt: pin B routed to IRQ 10
	Region 0: Memory at fdefc000 (32-bit, non-prefetchable) [size=16K]
	Capabilities: <access denied>
	Kernel modules: snd-hda-intel

Where do I need to report the missing configuration to alsa developers as advised in https://help.ubuntu.com/community/SoundTroubleshooting?

Any help appreciated

Thanks