Most individuals these days believe that all such plans should be reported on an FBAR.
So a stakeholder plan, a SIPP, a Group Person Pension, a personal pension, an old retirement annuity contract, an executive pension plan, a final salaary scheme etc etc would all reportable annually.
The FBAR Regs are annoyingly unclear on this, but they do discuss reporting interests in foreign trusts and arguably all such pension plans would be foreign trusts (govenment plaans especially unfunded ones are arguably different).