it seems like the lastest tarball i have tried have pb as it uses an old variable that has been removed from x264.
when trying to comile gstreamer-plugin-ugly with x264 i get the following error:

stx264enc.c: In function ‘gst_x264_enc_init_encoder’:
gstx264enc.c:585: error: ‘x264_param_t’ has no member named ‘b_bframe_pyramid’
make[3]: *** [libgstx264_la-gstx264enc.lo] Erreur 1

I contacted videolan dev on irc channel and they told me b_bframe_pyramid has been replaced with i_bframe_pyramid.
Then I patched the file ext/x264/gstx264enc.c and compilation worked fine.

here is the very simple diff

--- /tmp/gstx264enc.c	2009-11-13 19:16:37.335487579 -1000
+++ ext/x264/gstx264enc.c	2009-11-13 19:01:05.615494630 -1000
@@ -582,7 +582,7 @@
   encoder->x264param.analyse.i_noise_reduction = encoder->noise_reduction;
   encoder->x264param.i_frame_reference = encoder->ref;
   encoder->x264param.i_bframe = encoder->bframes;
-  encoder->x264param.b_bframe_pyramid = encoder->b_pyramid;
+  encoder->x264param.i_bframe_pyramid = encoder->b_pyramid;
 #if X264_BUILD < 63
   encoder->x264param.b_bframe_adaptive = encoder->b_adapt;
 #else

Can you consider adding this upstream?

thanks