Official Hackers Manual
Here's a list of pinouts for the various connectors and boards.
Here's a pic of the board, some of the pinouts can be seen on it. 
What does it have?
- TV out
- Stereo line out
- Stereo line in
- The UART lines can also be used as GPIO (six of them) and PWM lines (four of them).
Where can we get the connectors from?
- The connector appears to be a Tyco Electronics connector, part number 1717169-2
- The manufacturer does *not* stock these for engineering samples, and very few vendors carry them
- Community member WizardStan has ordered a bunch and is selling them at $2 a piece plus shipping from Canada, see here (thread) or here (article)
- Lithium polymer single cell battery
- 4000 mAH, 4 AH
- battery cover here: 
- reading out battery information: data provided by Battery and Power driver
- TD043MTEA1 datasheet
- LTPS (8-bit parallel input for R, G and B, with separate horizontal and vertical sync)
- UART2 and 3 are available via the EXT connector, and via internal solder pads on the latest revision
- UART2 appears to support hardware flow control with RTS/CTS lines
- 6 are available on the EXT connector
- 7 are internal, 2 of which can be used as extra shoulder buttons
- 1 located on the LCD cable
- Yes, 1.8V 10-pin (board label JTAG)
- One at 1.8V from the OMAP (board label I2C3-1V8)
- One at 2.8V (board label I2C3-2V8)
- No internal USB ports
This is the breakout board used by Pandora team members during development. Only a small number were made, and they are not available to the public. However a similar product (or gerber files) may be released in the future. A schematic for this board is available here: http://openpandora.ca/schematic/AV_Board_schematic.pdf