Folks at xda did it again. They have a pre rooted Android 3.2 firmware for the Galaxy Tab 10.1 3G model (P7500JJKJ6). They have just squeezed in the root functionality and other than that, there are no additions, enhancements or new apps in it. Installing the ROM is pretty easy. Just follow these instructions
* Download the P7500JJKJ6_Stock_Rom.zip install file (link)
* Put the install zip on to your internal storage
* Reboot into recovery mode (Power and Volume button next to power)
* Install the zip
* Reboot
Again, since this ROM is pre-rooted, there is no need root galaxy tab 10.1 after you have flashed it.