Gmail for iOS was updated today to version 2.2.7182, and folks who use the app to grab their Gmail-flavored email are going to be happy.
First, there's now a way to sign out of individual accounts. In the past, signing out of one account was impossible -- you had to sign out of all of them at once. Now it's possible to tap and hold an account avatar in the app sidebar, which brings up a Sign Out button for that account.
The second big feature in this update is that you can now specify whether a link to Google Maps, YouTube and other web links should open in Google's native apps (if they're installed) or a mobile web view. The options are enabled for the entire Gmail app, not just for individual accounts. If you prefer Chrome on iOS over Safari, you'll enjoy this feature (which can be turned off).
Finally, the Gmail app now provides search suggestions as you type. The suggestions should provide results based on addresses or subject lines for any of your Gmail accounts.