WP Calendar Functionality Like Drupal?

My client wants me to implement calendar functionality like she saw at http://mommypoppins.com/newyorkcitykids/ice-cream-whats-the-real-scoop

Click on the “days” in the “what do you want to do today” section and click on the events themselves. There’s some nice AJAX-y stuff going on, and the interface overall is pretty user-friendly.

Does anyone know of a WP plugin (or other method) that does anything similar? I do have a Google Calendar embedded on a page via an <iframe>, and I’ve been playing around with getting an “agenda view” (short text list) into the sidebar. But Google Calendar doesn’t give me much control over design or CSS stuff, and clicking an event opens a new window/tab. I’d rather do everything “in page” if possible.

Why does Drupal and Joomla seem to have snazzier stuff than WP?