Although it was most likely unintended, physbones prior to 1301 could have their stretch set to infinity via debug view. Physbones on the most recent open beta (Both 1.0 and 1.1) are now clamped to 5, even if max stretch is set to infinity in debug. This will unfortunately break avatar systems relying on infinite stretch.
I and probably many others would love to see it be implemented in 1.1 as a proper feature. (Or at least clamped at a much larger number)