The current distributive of Mobile OCR Engine 4.0 is not supporting Windows Phone 7
ABBYY was planning to add Windows Phone 7 support, but because of the fact that Microsoft is currently (?) not supporting native C++ code on the new operating system, it is not possible for ABBYY to provide the SDK.
Windows Phone 7 can not be supported in the nearest future, because only Silverlight and XNA with C# code is possible.
Never the less, please contact ABBYY Europe when you would like to be able to run OCR on Phone 7.
Things can change