IPv6 in -CURRENT?

I'm trying to set up a server running yesterday's -CURRENT as an IPv6 
router for the local network using a tunnel broker. The handbook and 
other howto documentation I've found seem pretty consistent on the 
necessary steps, but I'm not having any luck. Any time I try to ping6 
anything I get "ping6: sendmsg: No buffer space available". That and the 
fact that I never see any packets out my external interface destined for 
my broker's tunnel IP make me believe that something is broken locally. 
This is my first attempt to do anything IPv6 on FreeBSD so it's entirely 
possible I'm missing something obvious. Current config info below; let me 
know if I should include anything else.

### rc.conf ###
ipv6_enable="YES"
ipv6_gateway_enable="YES"
ipv6_defaultrouter="-interface gif0"
gif_interfaces="gif0"
gifconfig_gif0="MYIP4 BROKERIP4"
ipv6_ifconfig_gif0="TUNNELPREFIX::2 TUNNELPREFIX::1 prefixlen 128"
ipv6_firewall_enable="YES"
ipv6_firewall_type="open"

The gif0 interface appears normal after a reboot with inner and outer 
endpoints looking like they should, but packets just don't go anywhere.

I'll be routing a /64 for the rest of the network but wanted to get the 
tunnel working before I muddied the waters with that and rtadvd, etc. Do 
I need to assign IPv6 addresses to any other interfaces for the tunnel to 
work?

Any input appreciated!

JN