I am the person who started the 1860 Bug. Here is the last reply I got from the developers:

Unfortunately, no fix is likely to make it to this OS2008 release.
But we haven't forgotten about the problem.
To solve it properly, the VPN daemon needs to talk to icd (the system
connectivity service) and inform it of the new tunnel interface. This requires
a supporting API from icd which was not implemented in Chinook. We may still
come up with a specially hacked vpnc package (if only ifup/ifdown scripts need
to be changed) that will at least tell Mission Control about the IP address
obtained for the VPN. Please inform which VPN solution you use on your device,
what are the packages and where they came from; in time, we may post some
customized packages for testing through our garage project.

So it's not likely to be an easy solve. I have my n800 working with my trixbox 1.2.4 (with g729 BTW) and have not been able to use rtcomm over openvpn (VNC and telnet work fine).

So it's a matter of time, probably. Have anyone succeeded with other VPN solutions?