Very unlikely that any advanced nforce sound functions will work on linux soon.
The audio part used inside the nforce is very similar to the one used in intel's i810 chipset. The current nforce linux audio driver is therefore a little modded i810 audio driver.
To get all that dolby surround stuff and other things nvidia added a dolby surround encoder/decoder but for that no drivers exist for linux. Likely the digital audio part is related to the dolby encoder.