Google offers calendar, contact sync app for iPhone, Windows Mobile
Google Sync is using Microsoft ActiveSync push technology to keep your contacts and calendar appointment up to date. Once you set up your phone, your information should update continuously, with no user intervention required.
In order to synchronize your contact list, your phone will need to support SyncML. Google Sync is currently in beta, which means it's a real Google product. But it also means there may still be some kinks to work out. It's also important to note that Google Sync will replace all the data on your device with information from the server, so you'll want to make sure to back up your data before trying it out.