It was already among the leading Calendar/iCal replacement apps for productivity aficionados, and now BusyCal has received a boost of new functionality with the release of BusyCal 2. The update includes improved iCloud functionality, and is also compatible with Google Calendar and other services based on the CalDAV standard. It requires OS X 10.8 Mountain Lion; users of Leopard and Snow Leopard can still use BusyCal 1.6 to sync over the local network with 2.0 users.
BusyCal 2 adds natural language support for event entry, a live 10-day weather forecast and even a new heat map view that gives you a glimpse at how busy the next 12 months will be. The updated app also works hand in hand with new Mountain Lion features like Notification Center for updates and alerts.
A new menu bar applet (similar to Fantastical and Today) lets you browse the day's events without opening the full BusyCal application, and you can also use it to create new events and to-do reminders. In addition to the cloud service calendar access it offers, BusyCal retains its popular ability to sync calendars between instances of the app running on different Macs on the same LAN... with a caveat or two.
Users of BusyCal 1.6 should note that there are several functional changes from 1.6 to 2.0. As Apple's Sync Services framework is deprecated in Mountain Lion, features in BusyCal that leveraged it (crossover synchronization with iCal/Calendar, Outlook or Entourage; direct calendar sync via iTunes to iOS devices) are no longer available.
Since BusyCal 2.0 doesn't sync with calendar apps that support Exchange, the BC 1.x "hack" that allowed Outlook users to replicate their work calendars onto Google Calendar isn't possible in the new version. In fact, BusyCal 2 doesn't publish calendars to Google at all; they need to be created on the web side, then you can subscribe to them in the app. Another consequence of the rebuild is that LAN-shared calendars (not iCloud or Google hosted calendars) cannot be synced to iTunes devices or published to the cloud services; they are local network only.
BusyCal 2 carries over the same clean, accessible aesthetic of its predecessor, letting you view the upcoming days, weeks, months or even years without being overwhelmed. The app is available for US$29.99 via the App Store, but you can take it for a free 30-day test drive via the official website.