Run something like :
valgrind --tool=memcheck --leak-check=yes  --leak-resolution=high
--num-callers=30 gst-launch-0.8 filesrc location="Next-Sun, Linear PCM.au" !
auparse ....

You will get :

==10301== 28 bytes in 1 blocks are definitely lost in loss record 1447 of 2171
==10301==    at 0x1B907901: calloc (vg_replace_malloc.c:176)
==10301==    by 0x1BC0AFD3: g_malloc0 (gmem.c:154)
==10301==    by 0x1B9285E2: gst_caps_new_empty (gstcaps.c:81)
==10301==    by 0x1B92864B: gst_caps_new_simple (gstcaps.c:126)
==10301==    by 0x1BA32988: gst_auparse_chain (gstauparse.c:334)

since tempcaps are not freed in the chain function , here's the patch for it :

Use patch -p1 < patch in your plugins dir,...

diff -Naur gst-plugins-cvs-org/gst/auparse/gstauparse.c
gst-plugins-cvs/gst/auparse/gstauparse.c

--- gst-plugins-cvs-org/gst/auparse/gstauparse.c        2005-06-23
11:32:34.116399824 -0400
+++ gst-plugins-cvs/gst/auparse/gstauparse.c    2005-06-23
11:33:45.705516624 -0400
@@ -368,7 +368,8 @@
    GST_BUFFER_SIZE (newbuf) = size - (auparse->offset);

    gst_buffer_unref (buf);
-
+    gst_caps_free(tempcaps);
+
    gst_pad_push (auparse->srcpad, GST_DATA (newbuf));
    return;
  }