It's pretty easy to use Google calendar, email, and contacts in such a way as to instantly sync between your phone and computer. An impressive alternative to the more costly Blackberry exchange services and mobile me membership fees. Read more here.
I should add, that there are some pretty affordable third party software packages out there that sync your standard computer calendars like iCal and Outlook with Google Calendar. Once you've got these systems in place, keeping your personal contacts updated wherever you are is a breeze.