Talking about upsets:
Rian Sukmawan/Yonathan Suryatama Dasuki -- they are not exactly "young", but, I will consider them INA's no 2 pair after Markis Kido/Hendra Setiawan with 1 Int. Challenge and GP titles in 2007. Over the past 1 year since they were formed, they have beaten:
(1) Lee Jae Jin/Hwang Ji Man, the 2008 OG Bronze Medallist (2007 Chinese-Taipei Open GP Gold)
(2) Luluk Hadiyanto/Alvent Yulianto (2007 Denmark Super Series)
(3) Tadashi Otsuka/Keita Masuda (2008 German Open GP)
(4) Jens Eriksen/Martin Lundgaard Hansen (2008 Singapore Super Series)
Bona Septano/Mohd Ahsan -- with 1 Int. Challenge title in 2007 and the World University Badminton Championships title in 2008. Some of these might not be considered upsets, but, I will think these are notable victories:
(1) Cho Gun Woo/Yoo Yeon Seong (several times last year)
(2) Hoon Thien How/Ong Soon Hock (2008 Singapore Super Series)
(3) Simon Mollyhus/Anders Kristiansen (2008 Indonesia Super Series)
(4) Lim Khim Wah/Tan Bin Shen (2008 Thailand Open GP Gold)
(5) Gan Teik Chai/Lin Woon Fui (2008 Chinese-Taipei Open GP Gold)
Fran Kurniawan/Rendra Wijaya -- also won't consider them young, but, they are rising up the ranking tables very fast this year with 3 Int. Challenges and 1 Int. Series titles.
(1) Henri Kurniawan Saputra/Hendra Wijaya (2007 Dutch Open GP)
(2) Simon Mollyhus/Anders Kristiansen (2008 Spanish Int. Challenge)
Hendra A. Gunawan/Joko Riyadi -- not young for sure (esp AG) and a split is probably needed if they are not producing anything spectacular this year. But, they have beaten several top pairs in the past 2 years:
(1) Jung Jae Sung/Lee Yong Dae (2007 Swiss Super Series)
(2) Jens Eriksen/Martin Lundgaard Hansen (2007 Singapore Super Series)
(3) Tony Gunawan/Candra Wijaya (2007 China Super Series)
(4) Guo Zhendong/Xie Zhongbo (2008 Korea Super Series)
Other promising pairs:
Fernando Kurniawan/Lingga Lie (formed this year, Winner of 2 International Series in 2008)
Wifqi Windarto/Afiat Yuris Wirawan (Winner of 1 International Series in 2007, 1 Futures Series in 2008, and Runner-Up in 1 International Challenge in 2008)
(1) Mohd Razif Abdul Latif/Chan Peng Soon (2007 Thailand Open GP Gold)
(2) Goh Wei Shern/Ong Jian Guo (2008 Thailand International Series)
(3) Mak Hee Chun/Teo Kok Siang (2008 Thailand International Series)
Adi Chrisna Wijaya/Syahmie Syarif Radhitian
(1) Kwon Yi Goo/Koo Sung Hyun (2008 Indonesia International Challenge)
Rizky Yanu Kresnayadi/Albert Saputra
(1) Rian Sukmawan/Yonathan Suryatama Dasuki (2008 Indonesia Super Series)
On paper, INA have 1 really solid pair (Kido/Hendra), 4 established pairs (Rian/Yoke, Fran/Rendra, AG/Joko, Bona/Ahsan), and 4 promising pairs (21 or below), which are enough for backups. Of course, some of these players have beaten the MAS Junior pairs that are listed above.
On a thought, we are considered to be lucky if two of the young pairs and 2 of the established pairs can occupy the top 10 of the rankings table in the future.
My money is on Rian/Yoke or Fran/Rendra, Bona/Ahsan, Wifqi/Afiat, and Syahmie/Adi for the moment.