Should we merge squid3 and squid, and make squid3 an alias of squid?
Currently there's 74 questions tagged squid3, and 117 tagged squid. Of those tagged squid, a large portion appears to be tagged squid3 as well, and some of those tagged only with squid appears to be about squid3 as well.
In short the volume is not large enough to warrant version-specific tags in my opinion, and the lifecycle of releases is long enough that I doubt there will be much of a problem with users confusing versions. Squid2 was depreceated in 2011...