I saw an easy way to do this in Maya on TV. They were making fly-through logo's, but its the same concept.
Just create a flat plane and texture it with your logo. Draw your splines over the edges. Extrude a bit and you've got a basic 3D logo.
Please note, this is all just logic and reasoning. I have no real experience with modeling programs as none of the worthwhile ones are leagally free and easy to learn. The demo I saw used Maya's lightmap feature to create the splines according to the changes in color, and then a handy slider for the distance to extrude. This may or may not apply to specific modeling programs, its just a guideline.