Google posted a message on the Google Calendar discussion group that drops a hint that all the engineers on Google Calendar are working hard to get task lists into the service. This has been one of the most requested features since the service launched (and even before) -- which makes it surprising that it's still MIA.
Hey everyone - thanks for the loud and very clear feedback on your desire for a to-do/task list feature. We're pretty passionate about to- do lists here as well, and we've got something in the works. Of course, we're working to add our special Google secret sauce to the to- do lists space (which can take some time to get right,) so we don't have something to announce just yet, but the entire team is listening to these threads closely.
Please be patient - we'll have more to talk about soon.
This response came yesterday after a month of comments in a user-started "to-do list petition". What do you think? Is this one of the most important missing features in Google Calendar?