Yahoo sometimes cannot be pinged but is used as an example in the installation handbook. A simple solution would be to pick a more likely candidate for pinging and change that reference. Candidates might include: google.com sourceforge.net
I booted with various installation media, and had no problem reaching yahoo. I've been using Gentoo since 2004.3, and I've never had a problem pinging any site . . . as long as I remembered to properly copy resolv.conf *before* chrooting. Heh, sourceforge is a very bad idea, as their site is known for constantly being down, slow, and buggy. Thanks for the suggestion, though.
Josh, I think the reporter's issue is that some Yahoo's servers don't reply to ICMP echo requests. That has nothing to do with Gentoo installation media...
All yahoo.com servers responded to pings today. Maybe some of their servers do not respond, maybe.... Who knows? It's most likely a local problem, but, anyway, let's just ping www.gentoo.org. FYI, a very very long time ago, when swift wrote that bit, www.g.o did not respond to pings.