My apologies to anyone who has been trying to email me. I just noticed yesterday that I there is a problem with the MX records for vuser.org. It looks like I have a bogus CNAME record for '@' which I am working with GoDaddy to get sorted out. Until then, if you have questions about vuser or VUser::Google::ProvisioningAPI, ask in the vuser-users group and I'll help out there.
Updated 4 Mar 2009: Looks like I got my DNS problems fixed. Test emails have worked from various domains. Let the mail flow.