Following up a report on the users mailing list it seems the mosaic reprojection is not working anymore.
Using the reflector to get a reprojected image quickly (using the demo data), if I try with a vector layer:
everything works fine but if I try with a raster one:
I only get a gray image.
Also checked out with uDig to make sure it was not an oddity of the reflector and got a gray image there