We aren't planning to allow fractional zoom levels, but we have plans to make zoom smooth while keeping zoom level as integer value. Unfortunately, the change you requested is not in our plans for Q3 2013 and it does not seem to be a trivial one. I will make sure it is reconsidered when discussing our future plans, but I am afraid no certain time frame can be given at the moment. You can check when this feature will be available using our PITS:
Unfortunately there are no workarounds which can make zooming smooth in the current version of RadMap.