My first brush with Server Core in 2008 has been a mostly positive one, however it's a little daunting to finish installation and be dumped immediately at a command prompt.  My first thought was - hey, how can I setup the network?  This post will attempt to capture the basic steps that need to be performed to configure a Server Core installation.

Configure IP Address: netsh interface ipv4 set address "Local Area Connection" static <IP Address> <Subnet Mask> <Default Gateway>

Configure DNS: netsh interface ipv4 add dnsserver "Local Area Connection" <DNS Server IP> <index> (where index is a 1-based integer value for each DNS Server added)

Turn on Remote Administration (Terminal Services): cscript scregedit.wsf /ar <0=enabled, 1=disabled>

Turn off the Advanced Firewall: netsh advfirewall set domainprofile state off

Change Computer Name: netdom renamecomputer <current computer name> /newname:<new computer name> (Then restart using shutdown /r /t 0)

Join a Domain: netdom join <computer name> /domain:<domain name> /userd:<username> /passwordd:* (with *, you will be prompted to enter password)

Add user to local Administrators group: net localgroup Administrators /add <domain>\<username>   (Use /delete to remove specified user)

Special Thanks to Daniel Petri for a great Server Core basic setup reference!

From the Server Core blog, here's a posting with other common configuration scenarios (specifically adding roles and drivers).