Hi there,
The problem is already mentioned in the subject. For starters, I must admit, that I never had problems with X11 applications, including previous relases of Inkscape. I am using the ibook G4, so it is not related to the Intel architecture.
When I start Inkscape 0.45, I have a messeage about long time need for caching the fonts etc., and after clicking "OK" the Inkscape disappears from Dock, and in Console I can see following output:
bash: no job control in this shell
dyld: /Applications/Inkscape.app/Contents/Resources/bin/inkscape-bin Undefined symbols:
/Applications/Inkscape.app/Contents/Resources/lib/libfontconfig.1.dylib undefined reference to _FT_Get_BDF_Property expected to be defined in /usr/X11R6/lib/libfreetype.6.dylib
/Applications/Inkscape.app/Contents/Resources/lib/libfontconfig.1.dylib undefined reference to _FT_Load_Sfnt_Table expected to be defined in /usr/X11R6/lib/libfreetype.6.dylib
Some other people have the same problem on their Macs, and the bugs have been reported on bugtracker here:
http://sourceforge.net/tracker/index.php? func=detail&aid=1654068&group_id=93438&atid=604306
and here:
http://sourceforge.net/tracker/index.php? func=detail&aid=1652913&group_id=93438&atid=604306
Please, fix this bug ASAP, or find some remedy, if this is caused by local settings.