Before you go running off to download it the reports say that the version leaked is extremely unstable and missing the City of Jerusalem. 

Anyways, I think this is  a great example of why console devs hate the PC market.  Based on second-hand info I've gotten, there was an unofficial dev responce which basically said the game wasn't even finished yet.  This prompts me to wonder what kind of security precuations are being taken if a game that is probably 8GB is being stolen out from under their noses.  It sounds like a physical breach of security tbh.

If its a reviewer leak they could easily mark every version they give out and track down the leak, or even better they could require all preview and review copies be played via online authentication.  And in-house copies for the dev team could similarly require authentication from a local server to play.  These things are far from foolproof but they help, particularly the identification methods as it keeps people honest.  

I'm not saying it's their fault that people are pirating the game, but they need to take every precaution they can to protect their investments, and normally there would be no doubt this would hurt them since people who normally would buy  the game want to get it ASAP and cave in. Lucky for them it seems, you can't get very far in the game.... Honestly I'm thinking of trying it myself since we are more than a month away from launch...at the very least I know I can't finish the game so I won't have an excuse not to buy it.

I have mine pre-ordered....it better be finished :(

I remember playing the leaked version of half life 2 and wishing I hadn't bothered.
Your ideas to stop people leaking the game are good, but how much time/money would devs be willing to spend to stop people playing an unfinished game? What ever systems they can come up with, the piracy release groups will only take a few days/weeks to crack it.
Another thought is that this maybe a purposeful leak, in order to garner column inches as well as get the game some free beta testing.

 lol, talk about a paradox. 

Eh, I wouldn't try and get it anyway and I'm already skeptical of how poorly it's been optimized for the PC based on the specs that were released. 

 Actually that is the reason I was curious.  I had actually decided not to bother but I found out a friend had already had it.

Long story short, on his 8800 GTS 320 it was running at Max settings at a solid 60 FPS (vSync on) at 1680x1050.  I think he has 2 GB of RAM and a 6400+ X2 iirc.  So he definitely has a nice system.  He actually climbed up onto a tall tower and was panning around the view over the entire city and it was silky smooth still.  So I'm guessing that its a lot more optomised than people think since the GTS 320 has been known to have some framerate issues on taxing games due to its relatively small VRAM, particularly with AA enabled.  It will be hard to know how optimised it is without trying other cards though.

And I can tell you from my experience that its definitely not a stable build.  I would be surprised if it wasn't stable by the time it launches and quite honestly there is a good chance that this build was several weeks old when it was released. With that said its definitely more of a concern now than it was before.

@mistershine,

The time/money invested would be negligable even for small devs.  Actually a great example of a company that already does this is Valve.  They let people pre-download the game before it is released so that they don't bog down their servers on launch day.  Then when its released officially you unlock the game through an online authentication with steam.   

I actually don't think the release was intentional tbh...they could easily release a demo and accomplish roughly the same thing.  The only reason to do it this way is if they didn't want to put the effort into fixing the bugs they would have to fix anyways...which of course doesn't make a lot of sense.  Also this method of release reaches a lot more people who aren't even considering a purchase than it does people who can be pursuaded to make a purchase. 

Honestly I have no idea how or why it was released, but it does make my choice a bit more confusing.  Now I'm not sure if I want to make a day one purchase and instead wait to see if the crashing issues are dealt with.  But on the other hand it cleared up my concerns about optimisation.  So really I'm pretty much where I started. 

Its Nuked, reason is bad corrupt data non-working levels and not retail.

@Sqrl

So i guess i'll be able to play it on my system?
I have 2GB Ram, 8800GT 512MB, and a Core2Quad @ 2.4 GHz.

(Please say yes :P)

 Well the 8800 GT 512MB benchmarks better than the 8800 GTS 320MB across the board so I would definitely hope so....especially since I have the same card.