The ModBook is a conversion product made from a MacBook (or MacBook Pro for the ModBook Pro) and a Wacom touchscreen tablet. Axiotron partnered with TMO sponsor Other World Computing (OWC) to market and sell the devices.
TabletMac, however, uses an Apple trademarked name, Mac, in its own name, something that is often used to contest a trademark in the U.S. In this case, Apple would likely have been able to make an argument that Axiotron’s trademark could lead to confusion in the marketplace.
It’s also pertinent to note that Apple is rumored to be working on its own tablet form factor, though most credible reports point to an iPhone OS device and not a Mac OS X-based device. If such is the case, it’s highly unlikely that Apple would use the name TabletMac, or any iteration therein, for its as-yet unannounced tablet offering, making the transfer of ownership from Axiotron to Apple all but coincidental.