Using the server-gradients branch of cworth's cairo tree, the server crashes:

1472        ScreenPtr           pScreen = pPicture->pDrawable->pScreen;
(gdb) bt
#0  SetPictureTransform (pPicture=0x8566700, transform=0x85651c0)
    at picture.c:1472
#1  0x082ddee2 in ProcRenderSetPictureTransform (client=0x8564200)
    at render.c:1675
#2  0x082de944 in ProcRenderDispatch (client=0x0) at render.c:1992
#3  0x08089e5a in Dispatch () at dispatch.c:457
#4  0x0807436c in main (argc=3, argv=0xbfbfe83c, envp=0xbfbfe84c) at main.c:447