"If they are a Windows Outlook user forget about it, rarely does it work – often they have to manually reply" If he means that when using iCal to invite someon

"If they are a Windows Outlook user forget about it, rarely does it work – often they have to manually reply" If he means that when using iCal to invite someone on outlook then that's probably accurate, but Outlook 2010 has a pretty robust 'pick a meeting time' that works exactly as he described it should across an exchange server. You pick the attendee's it tells you what time works for everyone, and even shows (at a high level glance) which days of the week is best. In fact, at work, we have a room reservation system hooked up to it so it'll even suggest a room thats available and reserve it. You can attach meeting agenda's to outlook invites (and I believe you can do with Gmail and an add in?) Most of the features he described (except maybe the location aware stuff) work on Outlook & Google Calendar. Of course there a few things on both clients that I wish were designed a little better but the functionality he asks for is basically there already...