Hi
Maybe this may still help someone:
I had the same problem and fixed it by replacing all JSON encoding/decoding from using the class Services_JSON to the PHP5 build in functions json_encode()/json_decode().
I replaced usage in these files:
/plugins/tweet-blender/ws.php
/plugins/tweet-blender/lib/lib.php
I know the Services_JSON class was used for PHP4 compatibility, but that is not an issue for me and the built in functions are MUCH faster.
/Martin