The latest update for the Borderlands PC to version 1.41 with this patch, raising the level cap for all players. This patch is for retail editions only. [source]

Borderlands PC Update Version 1.40 Notes
* Level cap increase of 8 levels for all players. - Original Borderlands players will now be able to achieve level 58.
- Owners of The Secret Armory of General Knoxx can achieve a record setting increase to a maximum level of 69.
* Enemies now scale to new level caps throughout the whole game as long as playthrough 2 has been completed.
* Item drops (with the exception of COM Decks) will now scale to new enemy level caps. * DLC4 Achievement/Trophy glitches that have affected some users will now properly award players for obtaining these achievements.

  Posted by SLG_Rady