I think squid doesn't in any currently by Red Hat delivered version 
provide IPv6 support - platform independent.

I searched around a bit and noticed, that

  http://www.init.ca/debian/squid-IPv6/

provides IPv6 support but bases on cvs branch "squid-ipv6" and 
porting seems very hard to me (maybe because I'm not a good c 
expert), but a diff between the current Red Hat delivered version 
and the cvs snapshot of the squid-ipv6 branch shows lots of 
differences which must be very carefully ported.

But I also heard and read, that the current squid unstable has IPv6 
enabled, I didn't verify that yet, because Red Hat also isn't willing  
to ship development upstream versions...Bill Nottingham told me that 
a few days ago (but he even said this friendlier *smile*).

As long as missing IPv6 support is no major issue nobody of the Red 
Hat people will work out a patch, I think :-(

But I'm curious what's going up with IPv6 support in squid at Fedora 
now, because it's a (with the time) increasing issue...

Maybe also relevant links:
http://cvs.sourceforge.net/viewcvs.py/squid/squid/?only_with_tag=ipv6
http://devel.squid-cache.org/ipv6/

This needs to be fixed upstream before we can ship an ipv6-enabled 
squid.  File it in 
http://www.squid-cache.org/bugs/index.cgi 
or (best bet) help the squid folks get squid-3.0 final out, so that 
ipv6 support can be merged into it. 

Reopening, attaching to IPv6 blocker bug.

ipv6 support is in squid-3.0 (current unstable version) so we should wait to
first stable 3.0...