Unfortunately, there aren't a lot of books to read on SANs. I have an updated version of my book coming out in a couple months that addresses SANs in greater depth across more diverse technologies. It feels funny saying so, but I definitely recommend getting this when it comes out.
Other than that, Tom Clark's book is pretty good for understanding how Fibre Channel works and Alan Benner's and Robert Kembel's books on Fibre Channel, although they are both oriented to engineers. As far as magazines go, InfoStor publishes a lot of articles on SAN technology and products. A lot of the articles in InfoStor come from vendors, so you have to always consider the source of each article, but the editorial perspective of the magazine is excellent: open minded with healthy skepticism.
Other books on related topics that I really like are "In search of clusters" by Gregory Pfister and "The switch book" by Rich Seifert. Both are fantastic in their ability to mix humor with great descriptions of challenging material.
Editor's Note: If you would like to purchase or find out more about any of the books Marc references in his answer, please click on the appropriate title(s) and it will take you directly to techtarget.com's Learning Zone.
Update: Marc's new book, Building Storage Networks, Second Edition, is now available at searchStorage.com's Learning Zone
Fibre Channel; Gigabit Communications and I/O for Computer Networks
By Alan F. Benner
In Search of Clusters 2/E
By Gregory Pfister
The Switch Book: The Complete Guide to LAN Switching Technology
By Rich Seifert
This was first published in April 2001