The Salesforce.com Outbound Notification Web Services AP (App Setup / create / Workflow & Approvals / outbound Messages) creates a WSDL containing a Notification element that has a upperbound of 100;

<element name="Notification" maxOccurs="100" type="tns:ContactNotification"/>

this means that the maximum no of objects that can be sent in 1 outbound message is 100. Is this configurable?