I have Pedersen's, Beim's and Kindermann's books on the Leningrad.  I think both Pedersen's book and Beim's book are good introductions to the Leningrad, with Beim's book probably the better value since it is more recent.

Kindermann's book is, as noted in other replies, a repertoire book which concentrates on the 7...Qe8 lines, which is not really a disadvantage as Qe8 is probably the most theoretically respectable of Black's 7th moves anyway.  This is a serious theoretical work, and generally covers variations in more depth and suggests many interesting ideas that have not yet appeared in master games.  Kindermann writes excellent opening books (see, e.g., John Watson's review of Kindermann's book on the 7. Qg4 0-0 variation in the French Winawer, which I also have and think very highly of) and provides a repertoire that you could use against masters with confidence.  Moreover, I don't read German but I have had little difficulty following Kindermann's analysis because (i) he uses Informant symbols in evaluating virtually every line he covers; (ii) he provides a lot of complete games with thorough analysis; and (iii) by learning the meanings of a few German chess terms (see the German-English dictionary on the Kaissiber site noted above, which is excellent and which can be printed from the site) you can usually get a general idea about what Kindermann is saying, although probably some fine points will be missed.

      If you want to buy two books, I would recommend buying Beim's and Kindermann's.  Although you could wait for an English edition of the Kindermann book, I personally don't think that the relatively small amount of information you might miss because the text is in German (if you do a minimal amount of work on translation) necessarily justifies the wait.

      If you want to buy a single book, you should probably choose between Beim's and Kindermann's: which one is better for you depends on your playing strength, the level of your ambition, and the amount of time you have to devote to opening study.  From my perspective, (I am currently inactive, but have old ratings of 2360 FIDE, 2378 USCF), Kindermann's book is superior because it is more detailed and complete theory-wise, although Beim's book is also very useful.  For someone rated below 2000 USCF and who has a limited amount of time to study openings, the Beim book would probably be superior especially if you are taking up the Leningrad for the first time.  For someone in the 2000-2200 USCF range (or an ambitious lower-rated player) both books have their advantages and disadvantages.  For a player rated above 2200 USCF, I think that the Kindermann book is definitely the way to go.
   

    Hope this is helpful, and good luck!

                           - Geof

Stefan Kindermann sends his regards to Forum users, and states:
"Most probably there will be an updated and improved English version of the Leningrad book (I will stay with 7...De8 however) by Edition Olms next year."

Hi,
in germany after the game Freitag-Beim it is clear who is the expert. Freitag was prepared by his team-member Kindermann to nearly beat Beim in dutch-lenin.
See also: 
http://www.chessgate.de/training/training_kindermann/training_kindermann.html 
Teil 17: Eine Waffe gegen Holländisch-Leningrader: Das direkte 8.Te1!?

The Kindermann book is a repertoire book giving only "one best move" against whites approach. Sometimes only covered by analysis. 
If anyone has problems understanding parts of the german comment, ask me to translate.
I have limited time, so it will take some time for the answer.

To say it in one sentence: I recommend the book from Kindermann.
My DWZ is 1880, I am a german.

Best wishes 
Ralf 

According to the review it only covers 7...Qe8.

Leningrader System sounds like it's pretty much the best thing out there. Has anyone read parts of this book and what do you think of it? Would the German be difficult to understand for someone who only speaks English? Are there any people out there who have purchased chess books in languages they cannot speak or read? Just want to make sure I will be able to get as much out of the book as possible before I order it.

I think at this point I can say that a new survey, in Engish, on the Leningrad Dutch is most definitely needed. Until then, can people who play this opening post some of their notes, analysis, or variations that they like?

Not really sure what "AFAIK"  means, but Beim's book is definitely newer. I've heard great things about "Leningrader System", but is it:

1) available in the US?
2) possible to read and understand a chessbook in another language (I don't have any knowledge whatsoever of German so unless the book uses nothing but standard assessment/analysis symbols, I'll be lost!)

Well yes it does!  I myself don't study the 7...Qe8 or 7...c6 variations.  I prefer 7...Nc6 which neither book covers.  I will mention that Beim covers 1.d4 f5 2.e4 fxe4 3.Nc3 Nf6 4.Bg5 Nc6 5.d5 Ne5 6.Qe2 which could be dangerous to an unprepared player.  Is there a really good book on the Leningrad?

I have Pedersen's and Beim's book on the Leningrad.  There is certainly more material in Beim's book and the book is published in 2002 as opposed to the 1996 date on Pederson's book.  Pederson, however, does offer coverage of 1.c4 f5 if that is important to you.  The two authors certainly seem to have different opinions as to how Black should meet the unusual replies to the Dutch.  (I'm not really sure who I trust on this, but I tend to lean towards the GM.)  All in all, the're both pretty good books.