The source code for released wxPerl modules is available on CPAN.
The bleeding-edge sources are available through Subversion at sourceforge. Of course, these sources may not be suitable for use in your 'production' projects at any given time.
Anonymous Subversion access
svn co http://svn.code.sf.net/p/wxperl/code/wxPerl/trunk trunk
Browse Subversion sources
SourceForge offers a Subversion browser interface that can be used to look at Subversion sources, compare the differences between revisions and get the most up to date revision of a single file.
sourceforge svn browser