% ls -l 
lrwxrwxrwx  1 root root 42 2007-12-01 06:35 /usr/bin/htpasswd -> /usr/local/dh/apache/template/bin/htpasswd

% /usr/local/dh/apache/template/bin/httpd -l
Compiled-in modules:
  http_core.c
  mod_define.c
  mod_so.c
  mod_ssl.c
  mod_dosevasive.c
suexec: enabled; valid wrapper /usr/local/dh/apache/template/bin/suexec

% ls -1 /usr/local/dh/apache/template/libexec/ | grep so$
libdav.so
libhttpd.so
libperl.so
libphp4.so
libproxy.so
mod_access.so
mod_actions.so
mod_alias.so
mod_asis.so
mod_auth_anon.so
mod_auth_digest.so
mod_auth_mysql.so
mod_auth.so
mod_autoindex.so
mod_cern_meta.so
mod_cgi.so
mod_dir.so
mod_encoding.so
mod_env.so
mod_example.so
mod_expires.so
mod_fastcgi.so
mod_frontpage.so
mod_gzip.so
mod_headers.so
mod_imap.so
mod_include.so
mod_info.so
mod_limitipconn.so
mod_log_agent.so
mod_log_config.so
mod_log_forensic.so
mod_log_referer.so
mod_mime_magic.so
mod_mime.so
mod_mmap_static.so
mod_negotiation.so
mod_rewrite.so
mod_security.so
mod_setenvif.so
mod_speling.so
mod_status.so
mod_throttle.so
mod_unique_id.so
mod_userdir.so
mod_usertrack.so
mod_vhost_alias.so



readelf -V ?.so

.gnu.version section: http://www.linux-foundation.org/spec/booksets/LSB-Core-generic/LSB-Core-generic/symversion.html

http://people.redhat.com/drepper/symbol-versioning