Thank you for your interest.
As stated in previous posts from this thread, adding mono support for our controls will be a huge task. I admit that the mono project is now more mature and stable than ever before, however our controls call Windows functions that have no alternatives in mono. Moreover our controls are grown and now are more complex, which makes the task more time consuming.
Creating a framework which supports different platforms had always been a challenging task. Currently there are newer technologies with greater potential in this area. For example I would recommend you to consider Silverlight
and its mono based version - Moonlight
In conclusion, we just want to be sure that this is the right development direction according to our customers opinion. If more people request the feature, we can reconsider our plans.
Should you have any other questions, do not hesitate to ask.
the Telerik team