Google has a special desktop app that syncs your Exchange calendar to your Google calendar. It runs on a timer, shortest interval is 10 min.
http://www.google.com/support/calend...y?answer=89955
You can set it up to be 2 way, Google to Exchange only, or Exchange to Google only. My machine at work is always on, so I just installed it there (yay for being a developer and having full admin to my work box!). Otherwise you'd have to have Outlook on a home machine connected to your work exchange server.