1. An integrated workflow services system comprising: a host process; a workflow foundation runtime engine for executing workflows, wherein said workflow foundation runtime engine is hosted by said host process and has access to one or more runtime services available on said host process; a rules engine integrated with said workflow foundation runtime engine, wherein said rules engine has access to one or more runtime services accessible by said workflow foundation runtime engine: a workflow foundation library; a workflow having a plurality of activities comprising: an activity defining a ruleset, wherein said ruleset comprises a plurality of rules, wherein at least one of said plurality of rules is defined directly against said workflow, and wherein said activity has access to said rules engine that is able to evaluate said ruleset and to schedule one or more other activities for execution in accordance with accessed runtime information.