Chuck,
I ran into this same problem and was finally able to fix it...
The pkgIndex.tcl file in /opt/local/share/darwinports/pextlib1.0 (as well as in darwintrace1.0) is missing the following line:
package ifneeded Pextlib 1.0 [list load [file join $dir Pextlib.dylib]]
I don't have a pkgIndex.tcl file in /opt/local/share/darwinports/ pextlib1.0, the directory seems to be actually: /opt/local/share/darwinports/Tcl/pextlib1.0/
The Pextlib.dylib file is also not universal. I opened the DarwinPorts-1.3.1.pkg, extracted the Archive.pax.gz file, extracted the contents and copied the proper dylib file from there...
jeeeez :) _THAT_ worked :) Thank you very much, Ryan, Paul and Chuck for your hints. Now, I think that deserves some kind of explanation of the top page of MacPorts, don't you think ? JC