I've just created a 'powershell-users' group within Googlegroups.
What this gives the PowerShell community is a general mailing list for everyone to join. Google account required, but hopefully that won't be much of an issue.
I've considered creating a 'powershell-nntp' or such group, but with RSS being what it is today, that is likely a much better solution (having an RSS reader to take care of such things).
I am hoping this mailing list will be useful to users in general.
Group name: powershell-users
Description: Windows PowerShell users. This is mainly a group for Windows PowerShell users such as system administrators, database administrators, and anyone else interested in PowerShell.
Group/web address:
http://groups.google.com/group/powershell-users
Current email address:
powershell-users@googlegroups.com