I'd like to encourage everyone to promote the following (old) idea so it gets the Product Manager attention it deserves:

https://sites.secure.force.com/ideaexchange/ideaView?c=09a30000000D9xt&id=08730000000BrrCAAS

Workflows are such a great feature, but they are so horribly problematic due to the lack of this "idea" being implemented, i.e. that Workflows should trigger other Workflows.

Any workflow that ever does a "Field Update" puts the organization at risk for existing and future time-based workflows to misfire and normal workflows to not fire if there are ever conditions based on the field updated, which results in problems ranging from malfunction to data integrity loss requiring repair.

Essentially, the only "safe" workaround is to NEVER do a "Field Update" with a workflow, which means using Apex triggers instead of workflows, i.e. Code not Clicks.  Thats usually not practical so unless everyone reviews every other workflow's conditions before creating a new workflow with a field update they possibly will be breaking other workflows and it's completely unobvious.  It's just a mess.

I brought this up at DreamForce at the first question the Meet the Developers session.  Here's the audio:

http://www.salesforce.com/video/dreamforce-sessions09-backstagepass.jsp

The excuse why it isn't implemented is that it causes infinate loops, and if you believe them supposedly it's on the roadmap to "do something about" in the perhaps in the next year.  Odds are unless more vote on the idea, workflows will continue to just silently malfunction for those who don't understand, and those who do will be forced into much more complicated workarounds such as Apex triggers.