As Dave Hillman mentioned, many companies have been applying this technique 
for some time.  It has been my experience that using this process nearly 
always requires some design changes if the card was not originally intended 
for the process.  The papers cited by Dave touch on some of the design 
concerns.

Some other issues you may want to consider:
>>  Will your solder paste flux "escape" from inside the joint to the 
surface?  You may have to try different pastes than what you are currently 
using.
>>  Does your reflow process have sufficient thermal transfer capabilities 
to heat under the through hole component body and into the center of the 
PCB?  We have been "sold" on convection reflow but vapor phase may work as 
well.
>>  Will you be able to provide  enough solder paste to make an acceptable 
joint?  There are many ways to accomplish this but there are also a number 
of constraints.
>>  Which side you process first may have to be considered relative to how 
and when you will insert the component.

In all, we have been very pleased with the success of this technique and 
would like to encourage component suppliers to expand the availability of 
parts which can be used in this manner.  I would like to hear from others 
using this process.  Please feel free to contact me directly or post your 
comments to the TechNet.

Bill Barthel
Electronic Assembly Corp.
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(414) 751-3651