Gearbox went on to their forums to explain the upcoming title patch (affectionately called v1.41) for Borderlands. It is quite straight forward to understand.
* Level cap increase for all players of 8 levels. That means that all Borderlands players will now be able to achieve a new maximum level of 58.
* Owners of The Secret Armory of General Knoxx can achieve a record setting increase to a maximum level of 69.
* End game players that have completed playthrough 2 will see enemies scale to the new levels up to the new level cap. That means that if you’ve completed everything, you can play through the game again and again at a challenging level in order to find better and better loot.
* Item drops (with the exception of COM Decks) will also scale with higher level enemies to the new level cap. That means that this Title Update features the highest level weapons to date!
* Other fixes, including DLC4 Achievement/Trophy glitches that have affected some users and will be corrected to properly award players for obtaining these achievements no matter which order they were completed in.
There you have it. Don't own any of the DLC? Not a problem! Bam! Level cap increase for you, good sir. Feel like playing more with your character? Not a problem! Bam! Increased scalability of the monsters!
Gearbox says the patch is in certification mode, but they have no tentative date on when the patch will go live.