When I had my BlackBerry Bold I used the Google Sync for BlackBerry utility to keep my calendar updated with my Google Calendar since my Google Calendar was also synced to my Outlook/Exchange account. Google has now added contacts sync to the utility that makes it even more functional. If I could have gotten the OWA email to work then I probably could have skipped the desire for Exchange synching on the BlackBerry.
I don't know about you, but my Gmail contacts are a complete mess and when I tried to use the new MailShadowG client the other day I had over 2000 useless contacts (email addresses only) that were pulled into and messed up my clean Outlook contacts. I think Google needs to work on making the Gmail contacts a better system before I'll sync back up again and recommend you use a bit of caution before syncing up your BlackBerry device.