I don't use Google Calendar myself but I do have a BlackBerry so I'm passing this on for other BlackBerry owners who do. Google has released a utility for BlackBerry owners that keeps the calendar on the BB synced up with Google Calendar.
Sync your BlackBerry with Google Calendar - www.Tech-Dump.com
“Using your BlackBerry smartphone's native calendar, you can now access your Google calendar even when you don't have network coverage and be alerted for upcoming appointments with sound or vibration. Your Google Calendar stays synchronized whether you access it from your computer or your phone. You can add or edit entries right on your BlackBerry smartphone or on your Google Calendar on the web.â€
You can download the sync utility from Google.
Sync your BlackBerry with Google Calendar - www.Tech-Dump.com