A More Subtle Approach
A good default theme for any system is a versatile theme. We went with subtle gray gradients, monochromatic icons, soft shadows and pastel colors. The 2.1 default theme features tons of colorful icons that are all fighting for dominance. We're carefully sprinkling in color to important areas for 2.2. For instance, you'll see a colored icon when you hover on the submenu buttons:

The goals is for Projectfork to plug into any Joomla template and not clash with the surrounding styles. We also want this default theme to be very easy to customize.
New Control Panel

The Projectfork control panel is the nerve center for project managers and needed lots of rearranging. First off, we ditched the sidebar in favor of a 60/40 2 column cpanel. There will be 100% width panel positions (like Joomla module positions) on the top and bottom of the 2 column layout as well for things like the new Mini-cal Panel shown here. We've also worked on the output of Joomla modules used in Projectfork, such as the login module shown here ->
Updated Tasks View
We're working hard on emphasizing all the right things in the new Tasks display. The base table colors have been muted and the actions are hidden so you're not overwhelmed with data. Task actions will be displayed when hovering on the item. Table rows will be change color depending on the priority of the item.

Tabbed Views Instead of Fieldsets
Instead of long lists of fieldsets with tons of options in one view, we're putting Joomla's default tabs to use and breaking up the views for pages such as the Project add/edit page:

User Interface / User Experience
We've learned a ton about creating a more tactile user interface and providing feedback during the user experience, and how important these things are to a user. In the 2.2 interface everything gives you feedback.

When you interact with the interface, divs will glow, borders and text will change color, buttons will depress, inputs will highlight, and you'll feel like you're taking part of an experience.
Messages On Top
We're also making lots of little logical improvements like pushing the messages up to the top (duh).

Projectfork Theme Engine Improved
Many of these updates are made possible by the improvements to the Projectfork Theme Engine (thanks Tobias!). The theme developer's job is now easier than ever with things like a Panel Chrome in the theme (think Module Chrome from Joomla templates).
What'd We Miss?
Our changes are far from complete, so speak up! What drives you crazy about Projectfork's default theme. Please don't list features requests like "I want a Gantt chart" here.