More information from the D&DO forums

Originally Posted by Turbine

The Harbor Solo Option

Quests in the Harbor have a new option available to you, opening up solo gameplay during your character's earliest levels. In addition to the Normal, Hard and Elite settings already available for each dungeon, the Solo option allows you to take on a dungeon at a difficulty setting suited for a single player. When you enter a dungeon on the solo setting, it contains monsters and traps that can be defeated without the help of a party.

After completing the solo adventures, you will be better prepared to gather allies and gain the best Experience rewards and loot, only available at the higher difficulty settings. Solo mode will not unlock the Hard and Elite difficulty settings. To gain access to the increased danger and reward from the Harbor's higher difficulty settings, you will need to complete each dungeon on its Normal setting, just as you do today.

The Waterworks, Irestone Inlet and the Kobold Assault dungeons will remain areas that require a team to conquer. The Solo difficulty setting will not be available in these areas.

I like it.. In my opinion - there was a definite problem with players too young in their lives jumping into the Waterworks, Irestone, and KA dungeons without experiencing more extensive adventuring.. now maybe, this will encourage them to spend some time learning a little more about what adventuring is all about.