Is there a good "timeline" plugin for IC? We're thinking of having a timeline to show our customers so they can follow when a new product feature would be released, the date of the release, and a small description regarding the product feature.

No, but this would make for an interesting third party plugin.

You could potentially use Pages with a custom template. You will still need a custom database template.  This might be the fastest and cheapest way to accomplish what you want. 

If you'd like a standalone app, you can post your job details in Customization.