asterisk users - Sep 2005 - Why isn't 3-way calling a standard feature?

It appears that 3-way calling is only possible if you
connect an IP phone with this feature to Asterisk.  I
can't find any (free) IAX soft phones that do 3-way
calling.  Why is 3-way calling not a standard feature
of Asterisk and why don't any IAX soft phones offer
it?  Is it such a complicated matter?  Is it possible
to implement via the dial plan?  I don't see any
examples of this on www.voip-info.org :( .

I know conference bridging is standard (as long as you
have a Zaptel driver loaded).  Is it the standard work
around to transfer calls into a MeetMe extension and
then join the conference, thereby effectively creating
a 3-way call but a little more onerously?

Thanks,

Geoff Cleaves
Barcelona