I recently installed Gentoo from Knoppix. When installing, network connection was fine, but when I booted to Gentoo and tried to ping internet or lan I just got "Host is unreachable" or something like that. I readed FAQ from Gentoo forums. It said that I should check kernel modules. I ran make menuconfig and everything in Ethernet cards sections was loaded as a module. (Btw. I compiled kernel using genkernel when installing Gentoo if it matters).

Still I couldn't ping anywhere. Now I really don't know what is wrong. This is what ifconfig gives me about eth0:
This "Link encap:UNSPEC" seems to be a bit weird? Shouldn't there be Ethernet instead of UNSPEC?

Yes you are right, there should be Ethernet instead of UNSPEC. Moreover your MAC address is quite strange. Usually, it's something like that: 00:A1:C9:1A:3C:BA
So it seems to be a network layer 2 issue. Try to recompile your kernel and be sure to have this option: CONFIG_NET_ETHERNET=y

Oliv'