1. An integrated workflow services system having processor and memory 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 at least one of a plurality of runtime services available on said host process, said plurality of runtime services, comprising: a first runtime service that provides support for persisting a state of said workflow; and a second runtime service that provides tracking of said workflow's execution; a rules engine integrated with said workflow foundation runtime engine, wherein said rules engine has access to at least one of said plurality of 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.