Yes iOS (iPhone) devices can discover and will show all (iOS and non iOS) devices near by that are discoverable.
iOS devices will also pair and connect / interwork with all devices (non iOS also) that supports the corresponding profiles that iOS supports - example Headsets for Voice , stereo music, Bluetooth wireless key boards, mice etc. Here is the list of supported profiles by iOS devices - http://support.apple.com/kb/ht3647
MFi (Made for iPhone / iPad / iPod) is specific only for accessories connecting to iOS devices via bluetooth but not using standard profiles. (Either because the standard profiles does not allow the use case or because it uses a generic profile like SPP to communicate to the accessory specific application on the iOS device)