This is going to be a wee bit in the future, but for my first outing with SR4, I think I'm going to run a game set down in that most magical of places, Horrible Rac-- I mean Tir Tairngire. For now, I just want to brush up on the Tir, since I have played in all of one session that took place down there, and it's not terribly representative of life there. As rough a place as it is for non-elves, I'm pretty sure they don't commonly take people out into the wilderness and hunt them like game whilst toting assault rifles and RPG's.

Which takes us to the point of this post. I would like to know where I can get information on what things are like in the Tir. I would prefer stuff that is current as of 2072, but that's not strictly required. I'm guessing the Tir Tairngire sourcebook would be a good place to start. I've managed to get a quick peek at Sixth World Almanac, and found a little bit there, but not as much as I would like.

Any other books that would be good to browse?

They did in fact release a PDF that was made specifically for giving an update on what's going on in the Tir right now: Land of Promise.

It's as current as 2074, and is relatively inexpensive.

(not sure about the actual content, since I have yet to read it, although from what I understand, it's kinda written in a way that assumes that you've already read the original Tir Tairngire sourcebook and that you're already familiar with the basics of what goes down there)

You most certainly need the original Tir Tairngire sourcebook. Land of Promise was written as an update, it just didn't have the word count and space required to do a complete re-write, too. TT for sure. See if you can find Shadows of North America somewhere, as it also has a short chapter on the Tir that was their mid 2060's update (which was then followed up on by LoP).

I'd also suggest picking up Elven Blood, while you're at whatever pdf-outlet you like for Land of Promise. It's a set of five adventures (for like $7), one set in Seattle (but very elf-centric), one kicking off the in-Tir adventures (with a smuggling run into the country), and then all the rest are Tir Tairngire shenanigans, political entanglements (with the LoP-updated Princes), etc, etc. Fan reviews have been tremendously positive, it recently got Best Game (Collection) of 2012, and folks have said the adventures are great introductions to the game, and would be a great way to kick off a campaign -- so, well, I'm not gonna disagree with 'em. You can read a review of Elven Blood here, if it helps to take my advice on it with a pinch of salt: drivethrurpg review.

And yes, I'm sure it's crass to guide people towards buying books I happened to write, but...well...I'm just about the biggest Tir Tairngire fan in the world, so I worked really hard to get these updates written (in neither instance were there pre-existing plans to do anything more with the setting), because I wanted it to be a corner of the universe that people could sling dice and have fun in. So, well, yeah. I'm gonna be that crass guy, and suggest folks buy 'em. I don't get royalties or anything, I just want to hear cool stories about people playing in the Tir, is all.

It's okay to be proud of your work, Critias, imho
Those two pdfs are some of the really good SR4 publications and I've thoroughly enjoyed them. In fact, I'm running the intro from Elven Blood in a side project right now.

So, in conclusion and to provide a non-biased opinion : I thoroughly agree with what Critias said. While the original Tir Tairngire book may be hard to find nowadays (no idea if they re-printed it or made it available as pdf), SoNA and Land of Promise are good for the background and updates. You can also find a few pages in the 6th world almanac, if I'm not mistaken. And Elven Blood is just a jewel of adventure writing, and you'll get a warm, fuzzy feeling if you're like me and know the original Elven Fire. Fun!