Ireland's World Cup victories over Test-playing nations Pakistan and Bangladesh were enough to win them a place in the elite list of nations.
The points accrued from their success took them above Zimbabwe and Kenya.
Australia, who have enjoyed the only unbeaten run in this year's World Cup in the Caribbean, remain ahead of South Africa who were leading the standings going into the tournament.
Sri Lanka take on New Zealand in Jamaica on Tuesday, while Australia and South Africa meet in St Lucia on Wednesday in the semi-finals.
The seven-week World Cup culminates in the final in Bridgetown, Barbados on Saturday.
Batting power reflects semis' line-up: Seven of the top 10 batsmen in the latest ICC rankings are from teams involved in this week's World Cup semi-finals.
Of the top 10 only Kevin Pietersen, Ramnaresh Sarwan and Mahendra Singh Dhoni will not be in Jamaica or St Lucia on Tuesday and Wednesday for the penultimate stage of the competition.
Sri Lanka opener Sanath Jayasuriya has moved up to third following his run of good form while there have also been moves in the right direction for Sarwan of the West Indies, AB de Villiers and Herschelle Gibbs of South Africa and Australians Matthew Hayden and Michael Clarke.
Hayden has moved up one place to seventh spot and is enjoying his highest rating for nearly three years following his third century of the World Cup against New Zealand on Friday.
England's Pietersen is still on top spot, closely followed by Australia captain Ricky Ponting in second. Sarwan's good showing in the Super Eight stage of the tournament has propelled him up no fewer than 10 places to sixth.
In the bowling rankings, South Africa's Shaun Pollock is still in front but he is slowly being caught by Shane Bond and the latest Australian fast bowler to make a challenge, Nathan Bracken.
The 29-year-old New South Welshman has moved past his team-mate Glenn McGrath and now occupies third spot.
Another Australian to have an excellent tournament so far is Brad Hogg.
He has moved up nine places to 14th and 19 places since the World Cup began. Hogg's teammate Shaun Tait is also in impressive form, having moved up 66 places since the start of the tournament, into the top 50 for the first time.
ICC ODI Rankings:
Teams: 1) Australia (129 pts), 2) South Africa (125), 3) New Zealand (115), 4) Sri Lanka (110), 5) Pakistan (110), 6) India (106), 7) England (104), 8) West Indies (99), 9) Bangladesh (45), 10) Ireland (29), 11) Zimbabwe (22) and 12) Kenya (0).
Batsmen: 1) Kevin Pietersen (Eng, 827 pts); 2) Ricky Ponting (Aus, 804); 3) Sanath Jayasuriya (SL, 769); 4) Mike Hussey (Aus, 766); 5) Graeme Smith (RSA, 753); 6) Ramnaresh Sarwan (WI, 746); 7) Matthew Hayden (Aus, 743); 8) Mahendra Dhoni (Ind, 739); 9) Jacques Kallis (RSA, 733); 10) Andrew Symonds (Aus, 720).
Bowlers: 1) Shaun Pollock (RSA, 900 pts); 2) Shane Bond (NZ, 807); 3) Nathan Bracken (Aus, 784); 4) Chaminda Vaas (SL, 775); 5) Glenn McGrath (Aus, 765); 6) Muttiah Muralitharan (SL, 752); 7) Daniel Vettori (NZ, 703); 8) Makhaya Ntini (RSA, 697); 9) Brett Lee (Aus, 693); 10) Abdur Razzaq (Ban, 685).