I was randomly thinking about it and then looked it up.
Starting from May 2008 (New Zealand's tour of England and the Australia's tour of West Indies) upto and including the ongoing test matches, here is a list of test debutants.
Sri Lanka: Ajantha Mendis, Dammika Prasad, Tharanga Paranavitana, Angelo Mathews
Australia: Brad Haddin, Beau Casson, Cameron White, Peter Siddle, Jason Krejza, Doug Bollinger, Andrew Mcdonald, Ben Hilfenhaus, Phil Hughes, Marcus North, Bryce McGain
Bangladesh: Naeem Islam, Mahbubul Alam, Imrul Kayes, Raqibul Hasan, Rubel Hossain, Mahmuddullah
New Zealand: Daniel Flynn, Aaron Redmond, Gareth Hopkins, Jesse Ryder, Tim McIntosh, Martin Guptill
India: Amit Mishra, Murali Vijay
West Indies: Amit Jaggernauth, Llionel Baker, Brendan Nash, Llendl Simmons, Dale Richards, Omar Phillips, Ryan Austin, Travis Dowlin, Chadwick Walton, Kemar Roach, Nikita Miller
England: Darren Pattinson, Graeme Swann, Amjad Khan, Tim Bresnan, Graham Onions
South Africa: JP Duminy, Imraan Khan, Albie Morkel
Pakistan: Khurram Manzoor, Sohail Khan, Mohammad Talha, Mohammad Aamer, Abdur Rauf, Saeed Ajmal, Fawad Alam
That is an extraordinary number of test debutants!
And only the West Indies faced absurd circumstances that resulted in 7 debutants in their ongoing test against Bangladesh.
All the others are for genuine cricketing reasons, if you know what I mean.
I'm not sure if there has been another period in test cricket that has witnessed so many debuts.
There might be, but this to me looks like probably one of the largest number for 3 cricket seasons - 2008, 2008-09, and 2009 as defined on Cricinfo.
So what is it? Is a test cap easier to achieve these days? Or are several teams going through a rebuilding phase? Or have there been too many injuries? Or the boards are just feeling generous?
55 debutants in 15 months of test cricket; I can count only 20 out of them who are or will be regulars for their test teams.