Google Nexus One User Manual page 122

Gmail
To open your Inbox when Gmail is running
S Press Back
OR
S When reading a message, press Menu
OR
S When viewing a list of labeled conversations, press Menu
Back to Inbox.
To switch accounts
Gmail displays conversations and messages from one Google Account at a time. If
you have more than one account, you can open the Accounts screen to view how
many unread messages you have in each account and to switch accounts.
1 From your Inbox, press Menu
2 Touch the account that contains the email you want to read.
NOUG-2.1-update1-105
until you return to your Inbox.
and touch Accounts.
and touch Back to Inbox.
and touch More >
Nexus One User's Guide
122