I believe that they said in the info. session for the OSU Fisher College of Business that it is possible to transfer from PT to FT. The way that it came across was that it may not be the easiest thing to do, and they may not necessarily encourage this, but they won't stop you.
Probably the biggest reason for this is the structure of the 2 programs. The FT program requires you to have either already taken certain prereqs (stats, econ, accounting, etc...) or have to take them (at the grad school prices of course!). However, in the PT program (which requires at least 5 yrs. of full-time work experience), they do not have the prereqs. Also, in the FT program, you are required to choose a major, while the PT program just allows you to choose a "specialization" area, if you want. However, the PT program does have certain "core" classes that everyone has to take (finance, marketing & logistics, accounting, etc.)
Basically, the PT program gives you longer to finish (2-5 yrs., as opposed to the 2yrs. for FT), cuts out the prereqs (due to the work requirement, they figure that you'll have more practical experience), and gives priority scheduling for the evening sections. That's right, the PT classes are the same ones as for the FT students, only offered at night. If there are still seats available after the PT students have scheduled, they are opened up to the FT students. On the same note, if you're a PT student, and have some sort of crazy work schedule or something, and want to take a daytime section, you can do that too.
What I do like, also, is that there is absolutely no distinction on your diploma or transcript between the FT, PT, or Exec. programs. No matter which one you graduate from, you simply have an MBA.