Borderlands – Reach level 69 in Borderlands

I have the Xbox version, but the maximum level without DLC should be 58. With "The Secret Armory of General Knoxx" the maximum is 69 (it goes to eleven, har har).

"The Zombie Island of Dr. Ned" doesn't affect the maximum level. "Mad Moxxi's Underdome Riot" doesn't either, but it does provide 2 extra skill points you only normally get by ranking up. One for beating the "lesser challenge" (only 5 rounds) in each of the 3 stadiums during playthrough #1, and the other for doing the same in playthrough #2.

The level cap for all characters was increased by 8 with the release of patch 1.4.1. This makes a total of 69 skill points to earn, though the four gained from DLC's 2 and 4 will still require those add-ons (as they are mission rewards). (source)

Edit

Well since people are actually reading this, there's a little bit more information on each point.

The answers in order:

• Yes - All quests reset - The game begins just as though you had started at lvl 1 (minus the character selection, so you'll have to do everything over again (including the tutorial!)
• No - You keep everything - This is pretty straightforward, what you have on you at the end of playthrough 1 stays with you. However, items in playthrough 2 are scaled (see below on scaling). So you'll find the same named weapons but they will have better stats, so don't just ignore them.
• Yes - Mobs scale to your level -It is expected that after completing your first playthrough you will be around lvl 35 (give or take). Therefore when you start a new game, the mobs will have 35 added to their level (again give or take a level). Which is why specific enemies (like Crawmerax for example) have a set level. If you're looking to do the Secret Armory of General Knoxx, you should be lvl 50ish (about 2.5 playthroughs).
• No - You can go find it in playthrough 2, or you can access playthrough one with your current character (so if you have gained a level in playthrough 2, that level sticks when going back to playthrough 1). This includes any subsequent playthroughs.

Hope that helps!