You can set up a meeting similar to Outlook using the GMail event function and Google Calendar Synch.
Send the invitation by e-mail. When you recepient accepts the invitation, you’ll receive another e-mail. Your Google Calendars are updated
I use Google Calendar Synch to synchronize with Outlook Calendar, so I can synchronize the calendar on my iPod touch (through iTunes). I’m running Windows 7 and Office 2007 and the sych runs flawlessly. I’ve synched Office 2003 on Vista, although it wasn’t as reliable or easy to set up.
We’ve been using Google Wave more and more to communicate with our clients. I hope to see this functionality added soon.