This subject was discussed a few months ago (around 10/2007). But it was rather a discussion about whether to make a PA sound driver or not. I personally would love to see that happen, if not only because PA has some very nifty features, like per-app volume, transparent sink switching etc, some of which are impossible to emulate through the alsa pulse plugin. Also, then next Ubuntu and Fedora releases will have PA enabled by default so if Wine doesn't work with that well there will be complaints.
I switched my desktop to PA yesterday, got most apps working, and to my surprise even flash (netscape 32bit plugin in a 64bit browser). All apps that I need use PA natively, only Wine doesn't have a PA sound driver. Since winealsa.drv will stay the default driver for Linux for the foreseeable future, I started digging and hacking to see why it doesn't work with the alsa pulse plugin and what can be fixed. There are a few bug reports that track the winealsa.drv/PA issue, such as [1].
There is very little required to make it work. Only two tiny changes to the alsa pulse plugin (one can be described as a quirk, until I figure out how exactly the alsa API can be emulated using PA, seems to be a very specific issue in how Wine uses the alsa API since other apps work fine) and sound works perfectly (tested with foobar2000 and WoW, both playback and recording). alsa-1.0.16 was just released, so I hope the needed changes make it into the next version.
In the PA volume control, all wine apps show up under the same name: ALSA plug-in [wine-preloader] and thus share the same volume and sink preferences. The alsa plugin could try to do some /proc/self voodoo to extract the true exe name. But given the simplicity of the PA API (no hwparams negotiation, just request a format and you'll get it) and the current problems with the alsa pulse plugin, I think a true wine sound driver would be a viable alternative. I'm still waiting to hear from those people who have said that they have a wine PA driver working :)
tom