Highly unlikely there will be a WM6 upgrade for this phone, and due to the high cost of it, there don't seem to be enough units in circulation to garner enough interest in an AKU upgrade. There is an i760 that is soon-to-be released on Verizon, which is the upgrade to their i730. Verizon has 6-month exclusivity on the device so we should see a Sprint i860 some time next spring.
That's probably the only downside of this device. There aren't nearly as many owners of this phone as there are with the 6800, so we won't see as many device-specific hacks. Others, feel free to chime in and let me know if I'm on track with this or not.