PTmender

PTmender is a replacement for Helmut Dersch[*]'s PTStitcher. It is fully Open Source and it was written by Daniel M German. A multi-platform version is now included with the pano12 and pano13 libraries available at Sourceforge.

Most useful functionality of PTStitcher has already been implemented, particularly:

Compatibility with existing command line and script usage
Colour and brightness correction
Multiple TIFF output
PSD output with layer masks
Flattened TIFF, JPEG and PNG output

There is also new useful functionality not available in PTStitcher:

cropped TIFF output
LZW compression of TIFF output
All the new projections supported by Hugin such as multiplane and Pannini

Functionality that hasn't been implemented:

Support for VRML, PICT, QTVR, IVR
Support for other-than-rectilinear lenses such as fisheyes
Probably lots of other stuff