"To have one player from your squad nominated for an award like this would be a proud moment, but the fact that both Shane and Ryan are in contention should be looked on as a testament to the hard work and effort of the whole squad," said Gatland.
"Both have individual qualities, Shane Williams has been in sparkling form and not only lit up the Six Nations but also shone on our tour to South Africa in the summer.
"Ryan returned from injury just before the Six Nations to lead from the front and the leadership role he fulfils has been integral to our achievements and should not be underestimated.
"But to have two player's recognised in the top five of the world game is the highest accolade and the nation, together with all of the Wales coaches and national squad, should take great pride in that fact."
The IRB Player of the Year award winner will be announced at the IRB Awards in association with Emirates Airline in London on November 23.
Scotland scrum half Mike Blair, New Zealand fly half and 2005 IRB Player of the Year Dan Carter and Italy captain Sergio Parisse join Wales pair Williams and Jones in being been nominated for the Game's most prestigious award.
"The IRB Player of the Year Award is the ultimate accolade for a player and takes into account performances in all the major internationals played during the year including the RBS Six Nations, Tri Nations Series and the June-July tests," said International Rugby Board Chairman, Bernard Lapasset.
"The list of past winners of this coveted award is impressive and reads like a who's who of the international Game in recent years. Jonny Wilkinson, Schalk Burger, Richie McCaw, Fabien Galthie, Dan Carter, Keith Wood were all worthy recipients of the award, while Carter would be the first player to win twice should he be selected," added Lapasset.
The nominees were selected by the Awards' independent panel of judges, comprising former internationals with over 500 test caps between them. The panel, which also votes on the IRB Team and Coach of the Year during the same period, has deliberated over every major test this year.
Tana Umaga, Raphael Ibanez, Will Greenwood, Francois Pienaar, Agustin Pichot, Gavin Hastings, Scott Quinnell, Paul Wallace and convenor John Eales watched over 47 hours of action from 35 matches, awarding points to the three players they thought stood out in each match.
"Now that the shortlist has been selected the panel will reconvene during the November tests in the northern hemisphere when the IRB Player of the Year will be selected. The announcement will be made at the IRB Awards in association with Emirates Airline in London on November 23, which is the most prestigious annual celebration of the international Game," added Lapasset.
The IRB Player of the Year is one of 13 categories of awards that include the IRB Coach of the Year, IRB Team of the Year, IRB Sevens Player of the Year, IRB Junior Player of the Year and IRB Women's Personality of the Year. The event also recognises outstanding achievement and there are two awards run in conjunction with the International Rugby Players Association (IRPA); the IRPA Special Merit award and the IRPA Try of the Year.