You can use v.to.rast to transform all labeled (!) vectors into a raster map. Unlabeled vectors will be omitted.
Beware that the command uses the current region settings, so make sure they encompass the region you would like to transform into a raster map. Also, when creating fixed category area maps ("thematic maps") that don't need a high resolution, make sure that the resolution is not set too high, as that might make the transformation uneccessarily slow (see the chapter called The GRASS Region).
If you wish to interpolate raster data from vector data, several options exist: