The ldd output is misleading. What you want to run is
LD_LIBRARY_PATH=/path/to/firefox/installation ldd WeaveCrypto.so
Ubuntu doesn't play the nasty debian versioning games, as far as I know, so you should have a /usr/lib/firefox-3.0/libxpcom.so and so forth.
Not so sure about NSPR, but it should be able to find libnspr4.so from the Firefox installdir or from /usr/lib
The ldd output is misleading. What you want to run is
LD_LIBRARY_ PATH=/path/ to/firefox/ installation ldd WeaveCrypto.so
Ubuntu doesn't play the nasty debian versioning games, as far as I know, so you should have a /usr/lib/ firefox- 3.0/libxpcom. so and so forth.
Not so sure about NSPR, but it should be able to find libnspr4.so from the Firefox installdir or from /usr/lib