O’Reilly has just published Michael Bartosh’s Tiger server book “Mac OS X Tiger Server Administration”, which can be downloaded from the O’Reilly website. It’s a 330 pages PDF file and costs $20 USD.
My first impression is that it’s much more focused on typical setups than the Panther edition. Yet, at the same time it’s only 330 pages compared to 800 pages of the Panther edition. Though there are more specific tips on backup strategies, e.g., the Open Directory chapter is not as much in depth any more.
Yet, the Panther edition of the Bartosh book should be in your library anyway, so consider the Tiger book as an add-on and read both books. As a combination these works are the most comprehensive Mac OS X Server source available.