"This accessory is not supported by iPad. Ipad is not charging"

The iPad is not an iPod. The USB connector probably does not have enough power to charge the iPad.

Presently the iPad's dock/USB connection is only for syncing to a computer and charging. It is not a general data/audio connection.

The car's USB port probably is not charing the iPad because it does not supply sufficient current to show that the iPad is charging when awake. The iPad supplied wall charger puts out 10 watts while most USB ports on computers put out only 1.2 amp.

same issue with different dock speaker systems, could care less about chargeing, just want to be able to use the protable speake I have for when im on the go as the built in speaker *** for movies

My sister cannot use her iPad with either her Volvo S40 or her Pioneer VSX-1020-K, both of which work fine with my iPhone 3GS running iOS 4.

It's annoying.

I understand that the iPad with its huge battery draws more current. It's OK if it doesn't charge. I do want it to work with the accessories.

Can anyone at Apple let us know if iOS 4 for the iPad will fix these issues?

It may be more than Apple's problem to fix. There are several discussions in the iPod Touch forum that discuss a similar problem and one manufacturer has to do something to the car system to accommodate the iPod Touch's iOS4.1/ 4G.

If it's iOS4 then why does my iPhone 3GS running iOS4 work with both the car and home stereos?

The iPad runs ios3.

Maybe there is a hardware difference? For some reason Apple says the camera connection kit (CCK) does not work for the 3G phone. From Apple's page for the CCK:

The Camera Connector features a USB interface. Just plug it into the dock connector port on your iPad, then attach your digital camera or iPhone using a USB cable (not included). iPhone 3G is not supported.

I'm a sofware developer on PCs. There are layers to the software to access devices on a USB bus. There is the basic transmit/receive. On top of that is the code to support various devices like keyboards and mass storage devices.

This applies at both ends.

It's quite possible that the iPhone 3G does not hold its end up properly.

When you connect a 3G to a computer, does it look like a camera? Can you access it as if it were a disk drive with a DCIM folder in the root?

Furthermore, the iPad doc has an analog audio out jack.

http://store.apple.com/us/product/MC360ZM/A?fnode=MTc0MjU4NjE&mco=MTg2NDk1NTg

There is an accessory to deliver VGA video.

http://store.apple.com/us/product/MC552ZM/A?fnode=MTc0MjU4NjE&mco=MTczMTA1MTE

I really don't think it's a hardware issue.