I reckon Yahoo is speculating – and possibly worried – about what Google may offer, hence their most recent purchase: Upcoming.org

Via:

http://jeremy.zawodny.com/blog/archives/005477.html
http://www.waxy.org/archive/2005/10/04/yahoo_an.shtml
http://www.ysearchblog.com/archives/000193.html

Web based calendaring could be as useful as web-based email, assuming it can at least mirror the capabilities of client based calendars. For the first 10 years of email I used clients such as Outlook and in the last two years I have switched completely to web based email. It is very useful to be able to go to any web-capable device and get your mail. That said, web mail, such as gmail, is seriousliy handicapped without an integrated calendar. If anyone can take the next step in calendaring, it should be Google.

what about blogger and google talk? maybe too

i hope it will be based on open standards like iCal(or vCal is topper).

as Philipp mentioned it clould work with gmaps. so it could work with ride finder too. u have few thing to do in different places so it can show your way, maybe even some optimisations too ("i command you, u'll go that way!" ;)
2do/projects list
full integration with gmail of course but not "build-in" gmail. Contacts should be expanded (ie: theres no groups).

publishing non private calendar but with priv time 'areas' so people can know when u have time or maybe even some tool for planning meetings(u have data about free time from few cals and optimal meeting time suggestions)

ot. another wish: personalized web bookmarks expanded (like furl, spurl or just del.ico.us)

hmmmm..... all too much speculation. We all know that it more than likely will not integrate into their other online apps until project "Fusion" is complete. i do see great things to come when they decide to integrate...

If they integrated gmail properly it could potentially be the new hot invitation tool over evite.

I would love to have a calendar that integrated seamlessly with the google desktop application. I could access the same data from work or from home just the same way I access my gmail account. Thats really all I ask for from a calendar, that and an easy interface. So far google has had the easiest interfaces to work with (minus the fact that I can't sort my gmail *shakes fist*). Yahoo has a moderate interface but its integration with yahoo groups makes it somewhat clunky. Plus its too slow. I am hoping google has a better product, especially if its Ajax based. That will seriously speed things up.