Text messages are included, page 173 of the iphone_user_guide 5.1
Backing up with iCloud
iCloud automatically backs up to iPhone daily over Wi-Fi, when it’s connected to a power source and is locked. The date and time of the last backup is listed at the bottom of the Storage & Backup screen. iCloud backs up your:
Purchased music, TV shows, apps, and books
Photos and videos in your Camera Roll
iPhone settings
App data
Home screen and app organization
Messages (iMessage, SMS, and MMS)
Ringtones
Those apps mentioned in Settings/iCloud/Storage & Backup/Manage Storage/Your phone/Backup options are mostly 3rd party apps. To reduce the size of the next backup you can disable them, if you want to save some space in iCloud. But text messages are always included.