The urgent patch posted before makes a bug, so I cancel it and repost:
########## cut here ##########
--- /usr/share/guile/2.0/web/response.scm 2012-04-22 04:36:06.753878689 +0900
+++ response.scm 2012-04-27 19:54:55.539304271 +0900
@@ -217,13 +217,16 @@
 (define (read-response-body r)
   "Reads the response body from @var{r}, as a bytevector.  Returns
 @code{#f} if there was no response body."
+  (let ((te (response-transfer-encoding r)))
+    (if (and te (eq? 'chunked (car (car te))))
+        (get-bytevector-all (response-port r))
   (let ((nbytes (response-content-length r)))
     (and nbytes
          (let ((bv (get-bytevector-n (response-port r) nbytes)))
            (if (= (bytevector-length bv) nbytes)
                bv
                (bad-response "EOF while reading response body: ~a bytes of ~a"
-                            (bytevector-length bv) nbytes))))))
+                            (bytevector-length bv) nbytes))))))))
 
 (define (write-response-body r bv)
   "Write @var{body}, a bytevector, to the port corresponding to the HTTP
@@ -269,6 +272,7 @@
 (define-response-accessor content-type #f)
 (define-response-accessor expires #f)
 (define-response-accessor last-modified #f)
+(define-response-accessor transfer-encoding #f)
 
 ;; Response headers
 ;;
########## cut here ##########

2012/4/27 Sunjoong Lee <sunjoong@gmail.com>
+(define-response-accessor transfer-encoding '()) 
2012/4/27 Sunjoong Lee <sunjoong@gmail.com>
I googled and found http://tools.ietf.org/html/rfc2616 .

In a section of "4.4 Message Length":
  2.If a Transfer-Encoding header field (section 14.41) is present and
     has any value other than "identity", then the transfer-length is
     defined by use of the "chunked" transfer-coding (section 3.6),
     unless the message is terminated by closing the connection.
  3.If a Content-Length header field (section 14.13) is present, its
     decimal value in OCTETs represents both the entity-length and the
     transfer-length. The Content-Length header field MUST NOT be sent
     if these two lengths are different (i.e., if a Transfer-Encoding
     header field is present). If a message is received with both a
     Transfer-Encoding header field and a Content-Length header field,
     the latter MUST be ignored.