Dharmesh Shah and Brian Halligan wrote a very interesting blog entitled "Hindsight 2.0. Lessons from a Failed Web 2.0 Startup". The post is about Kiko, a once highly touted startup building a web 2.0 on line calendar. They had lots of buzz, VC money from Paul Graham, built with AJAX, and were considered cool. They are now up for sale on eBay...starting bid $50K.
I don't know the specifics of Kiko, but I do know that the calendar space is hard to crack. It is not about the technology...that is relatively simple. It is about existing calendars being entrenched in Microsoft Outlook, Lotus Notes, and to some degree Blackberry.
Calendars are a feature, not a company. Not only are calendars just a feature, but they have only been successful when integrated with your email/communication system. I don't know of a single calendar product that is successful on a stand alone basis. Even mighty Google has failed, with all its brand, money, and engineering prowess, in terms of market share, its calendar product is a failure. Kiko didn't stand a chance.
There are other companies doing on line calendars but the problem is always which calendar will be the primary consolidator of all entries, work, personal, or shared? Each calendar company wants to be the controlling or consolidating point. For most users they will not agree to give up their Outlook or Notes calendar, so it is a non starter.
This is why Ray Ozzie invented Simple Sharing Extensions (SSE), an extension to RSS. The idea behind Simple Sharing Extensions is to allow multi-directional synchronization of data and objects across multiple applications. Ray used the example of trying to synchronize his private/shared/public calendars with those of his wife. They used different tools and wanted to share pieces (but not all) of each calendar, and contacts, with each other, and associates.
SSE can help solve the calendar synching problem without requiring the user to choose a primary controlling calendar. Microsoft Outlook Calendar users can continue to use the Outlook Calendar for work, add personal events, and share selected calendar entries with other people. No one wants the hassle of maintaining separate calendars for work, personal, and shared items, and use different systems to do it.
An on line calendar does not solve the problem of sharing selected items with friends, or synching your work calendar on multiple devices, phones, etc. Web 2.0 or not, it was doomed to failure. Kiko is out of business and Google's calendar is a forgotten novelty.
There are lots of Web 2.0 failure stories but most of them are never told. They simply fade away, and with them, the lessons that could prevent another wave of bubble failures.