Head of Rugby World Cup, Kit McConnell, said: "Rugby Sevens has experienced a boom in global competitiveness since the last Rugby World Cup Sevens in Hong Kong in 2005.
"Therefore the Rugby World Cup Board agreed that a structure that reflected recent form of the qualified teams would be a better fit for ranking teams for Rugby World Cup Sevens 2009 in Dubai.
"The new rankings process will therefore fully reflect the competitiveness of the best men's national teams on the global IRB Sevens World Series.
"This falls into line with the process for Rugby World Cup 2011 when the IRB World Rankings will be used for the first time to seed the teams for the pool allocation draw."
The seeding for the men's competition will see the 12 IRB Sevens World Series core teams ranked entirely on their cumulative points total over the last two Series and the opening two rounds of the 2008/09 Series, which kicks off next month.
The top six teams will each top a competition pool with the teams ranked seven to 12 drawn in the second band.
The remaining 12 qualified teams, including Ireland, will then be ranked 13-24 based upon performances in their regional qualifiers and overall playing strength and randomly drawn into the third and fourth bands to complete the structure.
With Rugby World Cup Sevens 2009 being a landmark first for the women's game, the seeding structure is based upon the qualifying tournaments that are taking place across all six IRB regions this year.
IRB Sevens Manager Beth Coalter said: "Being the first women's RWC Sevens tournament, there is no historical base for assessing the relative strength of each region.
"The 16 women's teams have therefore been placed into a banded draw according to their playing strength at the RWC Sevens qualifiers."
The qualifiers will be split into four pools of four teams and each of the six regions will have a team represented in the first two bands of the pool structure.
"Once all 24 men's and 16 women's teams have been confirmed, the final seedings will be determined with the Rugby World Cup Sevens Draw taking place in Dubai in January," added Coalter.
The 2009 Rugby World Cup Sevens tournament will be played across two pitches at 'The Sevens', Emirates Airline's purpose-built facility, with the men's competition kicking off at 5pm (local time) on Thursday, March 5.
The inaugural women's competition will start on Friday, March 6 at 11am (local time).
Both the men's and women's matches will be played on the main pitch over the three days. The full competition schedule will be announced in due course.