I've went with IDoNotSnapshot after all: that's what also test_bugs_webservice is using.  Since there was missing documentation for translators property, I've added that too.


=== modified file 'lib/lp/services/worlddata/doc/language.txt'
--- lib/lp/services/worlddata/doc/language.txt	2010-02-17 10:39:16 +0000
+++ lib/lp/services/worlddata/doc/language.txt	2010-04-15 11:52:13 +0000
@@ -260,8 +260,40 @@ English name for a language including op
   Serbian ("Latn" variant)
 
 
+translators
+===========
+
+Property `translators` contains the list of `Person`s who are considered
+translators for this language.
+
+  >>> sr = language_set.getLanguageByCode('sr')
+  >>> list(sr.translators)
+  []
+
+To be considered a translator, they must have done some translations and
+have the language among their preferred languages.
+
+  >>> translator = factory.makePerson(name=u'serbian-translator')
+  >>> translator.addLanguage(sr)
+  >>> from canonical.testing import LaunchpadZopelessLayer
+  >>> LaunchpadZopelessLayer.commit()
+
+  # We need to fake some Karma.
+  >>> from lp.registry.model.karma import KarmaCategory, KarmaCache
+  >>> LaunchpadZopelessLayer.switchDbUser('karma')
+  >>> translations_category = KarmaCategory.selectOne(
+  ...     KarmaCategory.name=='translations')
+  >>> karma = KarmaCache(person=translator,
+  ...                    category=translations_category,
+  ...                    karmavalue=1)
+  >>> LaunchpadZopelessLayer.commit()
+  >>> LaunchpadZopelessLayer.switchDbUser('launchpad')
+  >>> [translator.name for translator in sr.translators]
+  [u'serbian-translator']
+
+
 =========
-countries
+Countries
 =========
 
 Property holding a list of countries a language is spoken in, and allowing

=== modified file 'lib/lp/services/worlddata/tests/test_doc.py'
--- lib/lp/services/worlddata/tests/test_doc.py	2009-06-30 16:56:07 +0000
+++ lib/lp/services/worlddata/tests/test_doc.py	2010-04-15 11:51:21 +0000
@@ -6,9 +6,20 @@ Run the doctests and pagetests.
 """
 
 import os
+
+from canonical.launchpad.testing.systemdocs import (
+    LayeredDocFileSuite, setUp, tearDown)
+from canonical.testing import LaunchpadZopelessLayer
+
 from lp.services.testing import build_test_suite
 
 here = os.path.dirname(os.path.realpath(__file__))
+special = {
+    'language.txt': LayeredDocFileSuite(
+        '../doc/language.txt',
+        layer=LaunchpadZopelessLayer,
+        setUp=setUp, tearDown=tearDown),
+    }
 
 def test_suite():
-    return build_test_suite(here)
+    return build_test_suite(here, special)

=== added file 'lib/lp/services/worlddata/tests/test_language.py'
--- lib/lp/services/worlddata/tests/test_language.py	1970-01-01 00:00:00 +0000
+++ lib/lp/services/worlddata/tests/test_language.py	2010-04-15 11:49:44 +0000
@@ -0,0 +1,21 @@
+# Copyright 2010 Canonical Ltd.  This software is licensed under the
+# GNU Affero General Public License version 3 (see the file LICENSE).
+
+__metaclass__ = type
+
+from canonical.testing import FunctionalLayer
+from lazr.lifecycle.interfaces import IDoNotSnapshot
+from lp.services.worlddata.interfaces.language import ILanguage
+from lp.testing import TestCaseWithFactory
+
+
+class TestLanguageWebservice(TestCaseWithFactory):
+    """Test Language web service API."""
+
+    layer = FunctionalLayer
+
+    def test_translators(self):
+        self.failUnless(
+            IDoNotSnapshot.providedBy(ILanguage['translators']),
+            "ILanguage.translators should not be included in snapshots, "
+            "see bug 553093.")