My T-Mobile SIM card has been living in my T-Mobile G1 Android device now for a few weeks and I continue to use it for phone calls, email, and web surfing. I was pleased to read that CompanionLink Sofware now has a way for you to sync your PIM data (no email) between Outlook, Lotus Notes, Palm Desktop, Novell Groupwise, and other clients to your T-Mobile G1. CompanionLink for Google Android is available now for US$29.95 with a free 14-day trial.
I have been using Google's free Calendar Sync utility to sync my Outlook calendar to my Google Calendar, but with this software you can also sync your contacts, tasks, and all of your unique calendar events.
I am still looking for an Exchange server solution on the G1 to really make it fully productive for me, but this is a nice step in the right direction.