In the previous MOSS 2007 version of SharePoint, there was an issue of delay activities in workflows not waking up because of how the SharePoint workflow runtime works.

 Sadly, Microsoft didn't reslove the issue by default with SharePoint 2010. You still have to jump through some hoops to get it running (usually after scratching your head as to why it doesn't work and scouring the internet for solutions).

 It turns out that the way to get things running is to dust off stsadm.exe and run the following commands:

stsadm -o setproperty -pn job-workflow -pv "Every 5 minutes between 0 and 59" -url http://webappurl
stsadm -o setproperty -pn workflow-eventdelivery-throttle -pv "45"

Thanks to StackOverflow for pointing me in the right direction.