diff --git a/CHANGES.txt b/CHANGES.txt
index f5058af..f8d4f03 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -10,7 +10,12 @@ Next release
   of Unicode values is done by the String type.  This differs from the
   previous behavior, where ``None`` implied that the encoding was
   ``utf-8``.  Pass the encoding as ``utf-8`` specifically to get the
-  older behavior back.
+  older behavior back.  This is in support of Deform.
+
+- The default ``err_template`` value attached to the ``colander.Date``
+  and ``colander.Datetime` types was changed.  It is now simply
+  ``Invalid date`` instead of ``_('${val} cannot be parsed as an
+  iso8601 date: ${err}')``.  This is in support of Deform.
 
 0.6.1 (2010-05-04)
 ------------------
diff --git a/colander/__init__.py b/colander/__init__.py
index 5c207c1..cdb3999 100644
--- a/colander/__init__.py
+++ b/colander/__init__.py
@@ -798,7 +798,7 @@ class Boolean(object):
         if not value:
             if node.required:
                 raise Invalid(node, _('Required'))
-            value = node.default
+            return node.default
         value = value.lower()
         if value in ('false', '0'):
             return False
@@ -944,11 +944,13 @@ class DateTime(object):
     You can adjust the error message reported by this class by
     changing its ``err_template`` attribute in a subclass on an
     instance of this class.  By default, the ``err_template``
-    attribute is the string ``${value} cannot be parsed as an iso8601
-    date: ${exc}``.  This string is used as the interpolation subject
-    of a dictionary composed of ``val`` and ``err``.  ``val`` and
-    ``err`` are the unvalidatable value and the exception caused
-    trying to convert the value, respectively.
+    attribute is the string ``Invalid date``.  This string is used as
+    the interpolation subject of a dictionary composed of ``val`` and
+    ``err``.  ``val`` and ``err`` are the unvalidatable value and the
+    exception caused trying to convert the value, respectively. These
+    may be used in an overridden err_template as ``${val}`` and
+    ``${err}`` respectively as necessary, e.g. ``_('${val} cannot be
+    parsed as an iso8601 date: ${err}')``.
 
     For convenience, this type is also willing to coerce
     ``datetime.date`` objects to a DateTime ISO string representation
@@ -964,7 +966,8 @@ class DateTime(object):
     The subnodes of the :class:`colander.SchemaNode` that wraps
     this type are ignored.
     """
-    err_template =  _('${val} cannot be parsed as an iso8601 date: ${err}')
+    err_template =  _('Invalid date')
+
     def __init__(self, default_tzinfo=None):
         if default_tzinfo is None:
             default_tzinfo = iso8601.iso8601.Utc()
@@ -1007,11 +1010,13 @@ class Date(object):
     You can adjust the error message reported by this class by
     changing its ``err_template`` attribute in a subclass on an
     instance of this class.  By default, the ``err_template``
-    attribute is the string ``${val} cannot be parsed as an iso8601
-    date: ${err}``.  This string is used as the interpolation subject
-    of a dictionary composed of ``val`` and ``err``.  ``val`` and
-    ``exc`` are the unvalidatable value and the exception caused
-    trying to convert the value, respectively.
+    attribute is the string ``Invalid date``.  This string is used as
+    the interpolation subject of a dictionary composed of ``val`` and
+    ``err``.  ``val`` and ``err`` are the unvalidatable value and the
+    exception caused trying to convert the value, respectively. These
+    may be used in an overridden err_template as ``${val}`` and
+    ``${err}`` respectively as necessary, e.g. ``_('${val} cannot be
+    parsed as an iso8601 date: ${err}')``.
 
     For convenience, this type is also willing to coerce
     ``datetime.datetime`` objects to a date-only ISO string
@@ -1028,7 +1033,7 @@ class Date(object):
     The subnodes of the :class:`colander.SchemaNode` that wraps
     this type are ignored.
     """
-    err_template =  _('${val} cannot be parsed as an iso8601 date: ${err}')
+    err_template =  _('Invalid date')
     def serialize(self, node, value):
         if isinstance(value, datetime.datetime):
             value = value.date()
diff --git a/docs/api.rst b/docs/api.rst
index 9e99d67..2fcc6b9 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -46,7 +46,11 @@ Exceptions
 
        An attribute not used internally by Colander, but which can be
        used by higher-level systems to attach arbitrary values to
-       Colander exception nodes.
+       Colander exception nodes.  For example, In the system named
+       Deform, which uses Colander schemas to define HTML form
+       renderings, the ``value`` is used when raising an exception
+       from a widget as the value which should be redisplayed when an
+       error is shown.
 
 Validators
 ~~~~~~~~~~