Installing SpatiaLite on Mac OS X

SpatiaLite and VirtualShape are SQLite extensions, so you need to install SQLite too, in order to allow them to operate.
There are various alternative ways you can follow at your choice:

the standard distribution way:
- Mac OS X supports the sqlite3 package.
  Very easily you have it already installed on your system
- Caveat: the sqlite3 currently distributed with Mac OS X doesn't supports the extension loading mechanism anyway
the doing it by hand way:
- go to the SQLite downloads and get the latest sqlite-version.osx-x86.bin.gz
- get the spatialite-macosx-universal-1.0.tar.gz
- gunzip what you've just downloaded, placing binaries and dynamic libraries somewhere [see note about dynamic libraries]
- to get started you can launch the sqlite3 program, and then .load 'SpatiaLite.dylib'
- Unhappily it doesn't seems to be any support available for Power PC processors
the GUI tool way:
- you can find lots of GUI tools supporting SQLite.
  May well be one of them supports extensions loading; all the ones I tested refused to do this.
- If you have best luck than me, then you simply have to get the spatialite-macosx-universal-1.0.tar.gz
- gunzip it somewhere [see note about dynamic libraries]
- then you start you preferred SQLite GUI tool and after .load 'SpatiaLite.dylib'
  If this works, you are ready to start

the SQLiteGeo way:

if you think the first two ways are too complicated for you, get the sqlitegeo-macosx-universal-1.0.tar.gz
this one is simply a standard sqlite3 slightly modified in order to support automatically loading for SpatiaLite and VirtualShape, and does not requires the sqlite3.dylib dynamic library to be installed at all
gunzip what you've just downloaded, placing binaries and dynamic libraries somewhere [see note about dynamic libraries]
to get started you can launch the SQLiteGeo program. That's all.
[you have not to type .load 'SpatiaLite.dylib' at all; it's implicit]

the SQLiteGeo package contains a copy of the libproj.dylib dynamic library.
[libproj.dylib doesn't seems to be widely available; the standard Mac OS X distribution offers no support at all]
but if you have already installed some kind of proj4 package its better you continue to use the already existing one, to avoid any confusion.

Then I suggest you to download the test.db database and follow the tutorial step by step;
it's the fastest way to become accustomed with SpatiaLite and VirtualShape

The xxxx-macosx-universal-xxxxx packages support any kind of Mac architecture
In the Apple jargon they are universal binaries [aka fat binaries], i.e. they can be used indifferently on any one of the following architectures:

32 bits Power PC processor [the so called ppc architecture]
64 bits Power PC processor [the so called ppc64 architecture]
32 bits Intel Core Duo processor [the so called i386 architecture]
64 bits Intel Core Duo processor [the so called x86_64 architecture]

The Mac OS X system will then automatically select the right version to use at run time, accordingly to current target architecture.

Managing dynamic libraries

On Mac OS X systems, dynamic libraries are identified by a .dylib suffix
Usually they have a plain name i.e. somelib.dylib, but usually they supports a version name as well, i.e. somelib.1.0.dylib
Usually this is accomplished simply by creating a symbolic link, as in:

$ ln -s somelib.1.0.dylib somelib.dylib

Usually dynamic libraries must be placed in the /usr/lib directory
You can as well keep yours dynamic libraries in any other directory at your choice, but in this case you have to set en environment variable, as in:

$ LD_LIBRARY_PATH=/Users/user_name/my_preferred_dylib_dir
$ export LD_LIBRARY_PATH