c++ -I../include -I./../include -g -O2 -Wall -c datebook.cc
In file included from /usr/include/g++-v3/backward/iostream.h:31,
                 from ../include/pi-datebook.hxx:7,
                 from ../include/pi-datebook.h:89,
                 from datebook.cc:11:
/usr/include/g++-v3/backward/backward_warning.h:32:2: warning: #warning 
This file includes at least one deprecated or antiquated header. Please 
consider using one of the 32 headers found in section 17.4.1.2 of the C++ 
standard. Examples include substituting the <X> header for the <X.h> 
header for C++ includes, or <sstream> instead of the deprecated header 
<strstream.h>. To disable this warning use -Wno-deprecated.
In file included from ../include/pi-datebook.h:89,
                 from datebook.cc:11:
../include/pi-datebook.hxx:37: friend declaration requires class-key, i.e.
   `friend class appointmentList_t'



Replaceing friend appointmentList_t; with friend class appointmentList_t; 
should do the trick; while at it, please update to the current version ;)