Judging from the number of agencies and organisations organising it, it seems to have gained a following. I guess there are a number of reasons for it.
- It is more memorable, as it is completely different from the usual tour package style
- It provides more interaction with the local common folks
- It provides those who are leading a comfortable life to have a chance to "sample" a little "hardship"
- It provides more satisfaction spiritually - a feel good phenomena
I guess to add to the overall increased interest in volunteering work, events like the 2004 tsunami and the 2008 Sichuan earthquake have put it into the spotlight. Recently, there is even a TV program on Channel U, "Stars for a Cause", where each week, a celebrity joins one of the many voluntourism programs out there, and they share their feelings and experiences. With all these publicity, I'm sure the general public is made more aware of the availability of such travel cum volunteering programs.
From the various feedback from the participants (and apparently, those celebrities as well), most of them felt that the "work" they do is minute compared to the joys they've achieved. In today's hectic and cold world, these "feel good" experiences are certainly "leisure" to the soul. While I have only joined one such program, I too have positive feedback. Perhaps in your next travel idea, do consider volunteer tourism!
Check out this forum for links to volunteering opportunities!