But although that question seems destined to remain unanswered for some time, his nomination as Sinn Fein's contact with the international body on decommissioning is viewed in London as a major step forward in the peace process.
The Londonderry republican has been an important figure in the republican movement since 1972, and has been at the heart of its leadership for almost two decades. In recent years he has been one of Gerry Adams' closest personal associates and one of the key players in the peace process.
With his reputation as a hardliner he commands respect throughout the IRA, a status which means he is seen as a guarantor that republicanism, for all its recent innovations, does not lose sight of its ultimate goals. This role as the man who provides assurance to the militants has been of vital importance at many points.
The decommissioning issue will put him to the test once again, since it is one of the thorniest issues of the peace process. On the one hand opinion throughout republicanism seems set against any decommissioning. On the other, decommissioning has been widely described as an indispensable part of the Good Friday agreement.
The British and Irish governments and the various other parties involved are all keen to make progress on decommissioning. It therefore seems unlikely that movement should take place on issues such as the new political structures and on the release of prisoners in the absence of some progress on decommissioning.
The two governments have deliberately stopped short of making decommissioning a condition for movement on the various other fronts. This is not, however, a sign of wishing to downgrade the issue, but is rather born of a tactical consideration that the republicans are more likely to respond to generalised pressure than to specific ultimatums and direct challenges.
Sinn Fein's approach to the decommissioning issue has been to take refuge in generalisations. The party's representatives, including Mr McGuinness, repeatedly say that they wish to see all guns taken out of Irish politics and an overall demilitarisation of the conflict.
Mr McGuinness has proved an electoral draw for Sinn Fein, becoming MP for Mid-Ulster earlier this year as well as winning a seat in the new Belfast assembly. He began his negotiating career in 1972 when, despite being on the run as an IRA suspect, he was one of a group of republicans flown to London by the RAF to meet the then Secretary of State for Northern Ireland, William Whitelaw.
The following year he was jailed for IRA membership in the Republic, and in 1974 was again locked up in the south on the same charge. He once said he had been "fired at by the British Army on countless occasions".
During the secret contacts between republicans and the Conservative government in the early Nineties, he acted as chief contact. When the talks eventually resumed, Sinn Fein described him as representing them but the Government insisted he had spoken for the IRA.
During the public talks of recent years he has again functioned as chief negotiator, meeting first government officials and then ministers on numerous occasions.
He once said that decommissioning was "a stalling device and a bogus argument" created by the Tory government to postpone talks. He has several times met Tony Blair, the Prime Minister.Reuse content