Heroku is PasS environment which supports PHP unofficially. It is missing some of extensions initially. One instance is mbstring.　However I noticed that mbstring is able to build on heroku run bash and can be loaded from project local php.ini configuration.
I put the mbstring.so on github. If you need it, just copy into your project and put php.ini which include:

extension=/app/www/mbstring.so

Example

This application is running on heroku with mbstring.

Enjoy php on heroku!

We released v0.8.2 of CandyCane just now. This release is bug fix release. If you are seeing some bugs with latest version archive, You can just replace sources with this release. Also I Ando did a small presentation at CakePHP2 meetup in Tokyo. In this session, I made a screen cast of CandyCane. This shows how installing CandyCane easy. If you haven’t installed CandyCane yet, I highly recommend at least watch this screen cast. It is only 2-minutes movie which is showing all steps of install and demo through main functionality.
Remember, installing CandyCane is so easy. Just extract archive, change some permission and click through installer. That is it!