linux

• LDAP Auth and Session HOWTO (does session)

Solaris

• nssldap mailing list archive. Contains references to solaris. Does session

IRIX

• Configuring LDAP (does session)

Tru64

• This PDF article describes configuring ldap auth on tru64. There doesn't appear to be anything about session information.
• Internet Express reportedly can do session - bundled free with current alphaservers, costs money for workstations or older alphaservers

misc

• LDAPzone
• Long pdf about ldap