The wxGTK-ebuild for the 2.4.2-series do not set the soname-field of the dynamic libraries. For example objdump -x /usr/lib/libwx_gtk2u-2.4.so|grep SONAME should return sth like SONAME libwx_gtk2u-2.4.so.0 The resolution is very simple, adding sth like myconf="${myconf} --enable-soname" in src_compile(), will create the corresponding soname-fields in the libraries.
that's a backwards ass test ... just run: readelf -d <lib> | grep SONAME
I know - it was a simple demonstration. And I use a python script with pyrex bindings to libelf for these things :) Anyway will this be fixed someday.
wxGTK-2.4 is being phased out, see Bug 145032. WONTFIX.