The senior patent holder is presumably now Ford Oxaal, who discusses his licensing policy, his relationship to iPIX, and the status of Helmut Dersch's "PT toolset" at http://www.pictosphere.com/kwx/faq.html .
I have made no attempt to evaluate the strength of his patents in light of the prior art, nor whether his patents are the only ones that might be enforced against the PT tools; but there is at least some indication that Oxaal has estopped himself against enforcing his patents against non-commercial use of whatever software components are part of "PT-Viewer". If his patents have any traction against libpano12, then it presumably cannot go into main, but may be suitable for non-free. Cheers, - Michael (IANADD, IANAL, TINLA)