Once you have a domain registered under your name and you want to move mailboxes to use the Google apps features, the migration is simple and you can use this link.
if you administer up to ten mailboxes, then the regular Google Apps will work for you, above that and you’ll need the Google Apps for business which will cost very low price for each mailbox.
Google provides a wizard which will lead you through the process. Know that the process involves changing the MX records where you domain exist to use Google MX records for pushing and sending emails.
Google provides the Google sync to synchronize your Google apps with your smart phone.
If you’re using symbian OS which used by Nokia phones, you need to install MFE (mail for exchange) to sync with Google Apps – not that even that Google doesn’t provide the known Exchange server features, her engine update data the same way exchange server does (in terms of ports, pop3 and IMAP).
After the installation, you need to create a new profile with those details:
Exchange server name: m.google.com
Secure connection: yes
Use default ports for syncing mail, calendar and contacts.
User name : your Google email address (not that if you migrated you domain MX as mentioned before, then your address will not have to be @gmail.com, but the address you always used for your account, for example @business.com)
Domain: you can leave it empty or write your domain name.
All other options open for your decision ( sync time, what to sync etc).
To read about iPhone syncing press here
To read about windows mobile press here