Yes, but be careful what commands you send to nvflash, some of them are dangerous. In particular, be careful of the various bat files that ship with the nvidia sdk. Do not execute them. They are all set up for the tegra 2 developer boards and they will repartition/reformat your tablet. Stay away from the --create command (which they use in all those bat files), plus anything with the word 'write' in it, at least until you have a usable backup.
On Windows, you'd want to install the Nvidia Tegra/Froyo pack (to get nvflash and the usb drivers), install the usb drivers, put your tablet into APX mode (again, hold down vol+ & vol- when turning the device on.. the device should go into a mode where it looks like it is turned off (screen blank) but your computer should see it as a usb device if it is connected via the mini<->usb cable and you have the nvidia usbpcdrivers installed)...
Then you'd want to go into directory nvflash was installed to (probably C:\Program Files\NVIDIA Corporation\android_tegra_250_FroyoOV5650 or.... Program Files (x86) if you're on Win x64) in a cmd terminal and type:
nvflash --bl bootloader.bin --getpartitiontable (filename)
That will retrieve the partition table from the device and store it into whatever (filename) you give it on your PC. You may have to make the filename some other directory than the current one if you're on Vista/W7 since they lock down the write permissions in Program Files directories. (You could also just modify the directory permissions if you want to do it that way, or copy all of the contents to another directory you have write permissions to, nvflash is self contained in terms of dll files all being in that directory).
Getting the partition table is the first step... there are some others, if anyone is willing to give it a try?