One of the new and more excitig features in LR 2.0 Beta is the Touchup Tool. You can access this by clicking the paintbrush in the develop module or by using the keyboard shortcut (K). It's easy to remember;
K for T O U C H U P...

Ok maybe not. But anyhow, press K to toggle the touchup tool.
The touchup tool is important because it offers non-destructive localized (manual) editing to a RAW file.
Here is a common problem image. This is a snapshot in natural, though less than optimal light.

The touchup tool is basically a cross between layer masks in Photoshop and control points in Nik Capture NX and Viveza. The key here is they are manually brushable/maskable for better control over images like portraits. You can brush on changes to Exposure, Brightness, Saturation, Clarity, and Tint. (Note: Tint is one step closer to adjusting localized White Balance!)
Note the five white touchup points in the below screen grab. A point is created where you start brushing. You can always select a point and edit it's features as needed. A single point can control multiple areas of the image (they don't have to be physically attached like a Nik Control Point.)

The touchup point on Zach's forehead is selected (and adjusted for exposure,) hence the black dot. I used three additional points for areas of the eyes as they needed different adjustment settings. The Irises were adjusted for exposure, clarity and saturation, the sclera (white) and catchlights were adjusted for exposure to brighten them, and the pupils were adjusted for exposure darkening them. The point in the background was adjusted for tint.
Each brushed area is repairable like a mask and you can reveal the mask by hovering your mouse over a specific point (see below). To delete a point, simply select it with a click of your mouse, and press the delete key. You can adjust the properties of the brush's size, feather and flow to create hard edges or believable blends. There is also an auto mask feature which helps confine the brushed area to a related area of the image. I find that for portraits and people the auto mask doesn't work so well, but for backgrounds and environments/landscapes/architecture, it works much more predictably.
The mask revealed:

The image before and after. I used an import profile which applies preset settings for camera calibration, tone curve, clarity, highlight recovery and vibrance. The only other manual adjustments I made besides the touchup tool were to add a little fill light and add a slight vignette with their respective sliders.
This was a 30 second edit!
