The gaps are essential, especially if the texture is low definition. The reason is the pixels will overlap the borders. It depends how you created your model, though. Also, higher end apps allow more options. Lightwave lets you adjust the size of the gap and whether the texture should continue around edges or not.

GILE[s] makes the task a bit easier because that is what it is designed for.

Will that be useful for making a lightmaping plugin?