I really want to purchase this game. Even though I have it on 360, I love the developments they've made on Steam. However I can't get a half decent frame rate from this game even if I turn everything down to low. 
 
My Macbook Pro = 2.26 GHz Dual Core Duo, 4GB Ram,   NVIDIA GeForce 9400M.

I run it on virtually maxed out settings on my laptop on windows, with a 2.0Ghz dual core intel processor, 3GB RAM and an NVIDIA GeForce 9500M.
 
So it seems that either the Mac version is extremely poorly optimised compared to the widows version, or something is wrong with your Macbook.

Hehe...Macs...

Hmm...Maybe because...ITS A MAC!!!

MACS SUCKZZZZ!!!!!!!!!!!!!111!!!11!
 
That's weird, Matty is probably right.  My laptop is about those specs, except my gpu is a 4650.  I don't have Team Fortress, but my laptop plays Portal fine.

I can run Crysis in medium settings on my 3 year old macbook pro which has lower specs than yours. 
I can run Borderlands and Mass Effect under wine in osx just fine. 
So i'd say they've done some terrible optimisation compared to the Windows version..but it's only just been released so give it time. 

Thats really weird.  Based on your specs I'd say you should be able to run the game just fine... and not with everything cranked down to low either.  I'd say just sit back and see what kind of updates they come up with.  I'm sure if you're having a problem other people are too, and they'll be quick to get started on a fix.

Don't get a mac if you want to play games. Thread over.

" Don't get a mac if you want to play games. Thread over. "

I've ran this game on my 06' Macbook. What settings are you using?

" Don't get a mac if you want to play games. Thread over. "

Why would you want to play TF2 on a mac? 
You can't even cloak as a spy...

I was a little disappointed when I first ran Portal on my MBP to see that the ran way better under my old Vista boot camp than it did natively in OSX. There've been patches every week making improvements and there's no doubt it'll be improving over the next few years but for now I'll stick my desktop for the more intense games and leave my MBP to handle Telltale, Civ, etc.

I can run Crysis on Max settings at 1920x1080 and get like 10-15 frames on my laptop, and if I bring it down to 1280x720 I can get well over 30, so I assume I could play Team Fortress with no hitches.

It's because of the drivers. Valve has said that even though the game was re-written to be native in OS X, the drivers that Macs have used were never meant to be used for gaming- as such, the game runs much worse than it does on a PC. The only solution is to wait until nVidia/ATI makes new drivers for OS X, and then Apple pushes them out in a software update.

" @Djeffers03 said:

" Don't get a mac if you want to play games. Thread over. "

True. Thats the only bullet point to get a PC is the fact that they play games. EDIT:And Macs can also....so,again the point in buying a PC would be? "

Just complain to apple that your mac doesn't work and they will fix it right? Cuz they are the only ones who can......

" Why would you want to play TF2 on a mac? You can't even cloak as a spy... "

I had problems running Team Fortress 2 on my Mac as well. The game was so laggy, making it unplayable. Half-Life 2 and Portal work fine though. I think Mac can't handle big online/ multiplayer games.

" @Djeffers03 said:

" Don't get a mac if you want to play games. Thread over. "

True. Thats the only bullet point to get a PC is the fact that they play games. EDIT:And Macs can also....so,again the point in buying a PC would be? "

 I am running it on a macbook pro as well, similar specs and havent had a problem at all... and our macbook pros have very similar specs... your doing something wrong.    

10.6.4 was causing issues with steam. Valve suggested not to update. This could very well happen with Windows too.

Im on a pc. Where mah i5's at? :D

My Macbook has an integrated graphics card that is incompatible with most Steam games.

I think it's a combination of many factors. The "faulty" Mac update, the fact that Mac Nvidia drivers haven't been updated in ages, a poorly optimized mac port, and the fact that the 9400m integrated is woefully underpowered (my old Thinkpad with a low-end business graphics card got better performance in Half-Life 2. I could max things out just fine on it, whereas the mac port runs merely okay at medium-high settings).
 
Things will improve. Or at least, they will if Apple is serious about gaming (and they should be). The number one thing they need to allow is regular video driver updates. The unfortunate thing is that Apple doesn't really treat their "old" hardware right; they'll be quick to let support lapse once they've released another series of Macbooks.