I emailed the Duokan guys with a few questions and they answered me real quick. Maybe it's useful to you.
Questions from me:
"1) Will you release a version for the Kindle 4/Touch?
2) Is there a chance you will develop a browser as a part of the package - that will be able to download all kinds of files? (pdf, epub, etc).
3) Are you working on support for non-english latin script in epubs - such as german, scandinavian etc?
Keep up your good work!"
Answers from Duokan:
Just quick answers:
1.We are trying to find out a way on jailbreaking, package installation, and platform issue. So K4 support is in plan but not soon.
2. No such plan.
3.We are working on software which support most of the popular language. Some of work items are getting low priority because of limited resource. We could do some balance in latter development.