IWB format (Common File Format) is generally well supported in SMART software, so you should have no trouble in import *.iwb files to SMART Notebook software and save the information from it as *.notebook file.
Convert Common File Format file to SMART Notebook data file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert iwb to notebook on Windows
A collaborative learning software
Convert from iwb file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.