diff --git a/lib/galaxy/model/mapping.py b/lib/galaxy/model/mapping.py
index 811f6583f75..3a2cea873a2 100644
--- a/lib/galaxy/model/mapping.py
+++ b/lib/galaxy/model/mapping.py
@@ -14,6 +14,7 @@ try: pkg_resources.require( "psycopg2" )
 except: pass
 
 import sys
+import datetime
 
 from sqlalchemy.ext.sessioncontext import SessionContext
 from sqlalchemy.ext.assignmapper import assign_mapper
@@ -26,19 +27,27 @@ from galaxy.util.bunch import Bunch
 metadata = DynamicMetaData( threadlocal=False )
 context = SessionContext( create_session ) 
 
-now = func.current_timestamp( type=DateTime ) 
+# NOTE REGARDING TIMESTAMPS:
+#   It is currently difficult to have the timestamps calculated by the 
+#   database in a portable way, so we're doing it in the client. This
+#   also saves us from needing to postfetch on postgres. HOWEVER: it
+#   relies on the client's clock being set correctly, so if clustering
+#   web servers, use a time server to ensure synchronization
+
+# Return the current time in UTC without any timezone information
+now = datetime.datetime.utcnow
 
 User.table = Table( "galaxy_user", metadata,
     Column( "id", Integer, primary_key=True),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
-    Column( "update_time", DateTime, PassiveDefault( now ), onupdate=now ),
+    Column( "create_time", DateTime, default=now ),
+    Column( "update_time", DateTime, default=now, onupdate=now ),
     Column( "email", TrimmedString( 255 ), nullable=False ),
     Column( "password", TrimmedString( 40 ), nullable=False ) )
 
 History.table = Table( "history", metadata,
     Column( "id", Integer, primary_key=True),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
-    Column( "update_time", DateTime, PassiveDefault( now ), onupdate=now ),
+    Column( "create_time", DateTime, default=now ),
+    Column( "update_time", DateTime, default=now, onupdate=now ),
     Column( "user_id", Integer, ForeignKey( "galaxy_user.id" ) ),
     Column( "name", TrimmedString( 255 ) ),
     Column( "hid_counter", Integer, default=1 ),
@@ -54,8 +63,8 @@ History.table = Table( "history", metadata,
 
 Dataset.table = Table( "dataset", metadata, 
     Column( "id", Integer, primary_key=True ),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
-    Column( "update_time", DateTime, PassiveDefault( now ), onupdate=now ),
+    Column( "create_time", DateTime, default=now ),
+    Column( "update_time", DateTime, default=now, onupdate=now ),
     Column( "hid", Integer ),
     Column( "history_id", Integer, ForeignKey( "history.id" ) ),
     Column( "name", TrimmedString( 255 ) ),
@@ -76,8 +85,8 @@ Dataset.table = Table( "dataset", metadata,
 
 DatasetFileName.table = Table( "dataset_filename", metadata,
     Column( "id", Integer, primary_key=True ),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
-    Column( "update_time", DateTime, PassiveDefault( now ), onupdate=now ),
+    Column( "create_time", DateTime, default=now ),
+    Column( "update_time", DateTime, default=now, onupdate=now ),
     Column( "filename", TEXT ),
     Column( "extra_files_path", TEXT, nullable=True, default=None ),
     Column( "readonly", Boolean, default=False ) )
@@ -97,8 +106,8 @@ DatasetChildAssociation.table = Table( "dataset_child_association", metadata,
     
 Job.table = Table( "job", metadata,
     Column( "id", Integer, primary_key=True ),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
-    Column( "update_time", DateTime, PassiveDefault( now ), onupdate=now ),
+    Column( "create_time", DateTime, default=now ),
+    Column( "update_time", DateTime, default=now, onupdate=now ),
     Column( "history_id", Integer, ForeignKey( "history.id" ) ),
     Column( "tool_id", String( 255 ) ),
     Column( "state", String( 64 ) ),
@@ -130,8 +139,8 @@ JobToOutputDatasetAssociation.table = Table( "job_to_output_dataset", metadata,
     
 Event.table = Table( "event", metadata, 
     Column( "id", Integer, primary_key=True ),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
-    Column( "update_time", DateTime, PassiveDefault( now ), onupdate=now ),
+    Column( "create_time", DateTime, default=now ),
+    Column( "update_time", DateTime, default=now, onupdate=now ),
     Column( "history_id", Integer, ForeignKey( "history.id" ), nullable=True ),
     Column( "user_id", Integer, ForeignKey( "galaxy_user.id" ), nullable=True ),
     Column( "message", TrimmedString( 1024 ) ),
@@ -140,8 +149,8 @@ Event.table = Table( "event", metadata,
 
 GalaxySession.table = Table( "galaxy_session", metadata,
     Column( "id", Integer, primary_key=True ),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
-    Column( "update_time", DateTime, PassiveDefault( now ), onupdate=now ),
+    Column( "create_time", DateTime, default=now ),
+    Column( "update_time", DateTime, default=now, onupdate=now ),
     Column( "user_id", Integer, ForeignKey( "galaxy_user.id" ), nullable=True ),
     Column( "remote_host", String( 255 ) ),
     Column( "remote_addr", String( 255 ) ),
@@ -149,14 +158,14 @@ GalaxySession.table = Table( "galaxy_session", metadata,
 
 GalaxySessionToHistoryAssociation.table = Table( "galaxy_session_to_history", metadata,
     Column( "id", Integer, primary_key=True ),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
+    Column( "create_time", DateTime, default=now ),
     Column( "session_id", Integer, ForeignKey( "galaxy_session.id" ) ),
     Column( "history_id", Integer, ForeignKey( "history.id" ) ) )
 
 StoredWorkflow.table = Table( "stored_workflow", metadata,
     Column( "id", Integer, primary_key=True ),
-    Column( "create_time", DateTime, PassiveDefault( now ) ),
-    Column( "update_time", DateTime, PassiveDefault( now ), onupdate=now ),
+    Column( "create_time", DateTime, default=now ),
+    Column( "update_time", DateTime, default=now, onupdate=now ),
     Column( "name", String ),
     Column( "user_id", Integer, ForeignKey( "galaxy_user.id" ), nullable=False ),
     Column( "encoded_value", String )