On the Gearbox forums someone has went through the new patch for the PC version and found files for new DLC.
 
Here's the link to the Gearbox forums. 
HUGE SPOILERS. DO NOT CLICK IF YOU DON"T WANT SPOILERS. PRETTY MUCH EVERYTHING ABOUT THE DLC IS IN THE POST.
 http://gbxforums.gearboxsoftware.com/showthread.php?t=108873
 
So who wants some more Borderlands DLC? What does everyone want out of it? 

Does anyone think that it's been too long since the last one for this to matter?

God, that list looks awesome. Too bad I don't have Borderlands anymore...

Level cap increase? Sounds awesome though.

Oh fuck yes. 

Made my bloody week!
 
I love Borderlands!
Gimme gimme gimme!

I'm down!  The list of stuff sounds awesome, and the intro part with Marcus is classic!

Oh yes, yes yes!!!!!! More Borderlands, yes please. I wonder if there will be a level cap increase.   I mean, people are just killing Crawmerax in no time these days... I'd like to finally go and kill his stupid face solo though.

I'm crossing my fingers that having Marcus as a primary character will mean more unique guns. 
That or a level cap increase and I'd be in :D

Super excited. I could really go for some new Borderlands content after all this time.
 
Ninja Claptrap? Sold.

Smokin' Jesus Titty Cinnamon!

I think I'm about ready to go back and play some more Borderlands... but I still haven't played any of the existing DLC so this doesn't really affect me.

Fuck yes.