I would like to see:
? iCloud sync for keyboard shortcuts and "Now Playing" song in Music.app.
? iCloud icon next to undownloaded iTunes Match songs in Cover Flow and Spotlight.
? Have toggle for hiding undownloaded iTunes Match work across in-app access, Cover Flow, and Spotlight.
? Ability to message (or, actually, just the whole action menu) from the Lockscreen camera.
? Add 2-minute interval repeats for Reminders just like Messages.
? "Clear All" button for completed list in Reminders.app.
? Ability to reorder reminders within a list.
? Precision time selection for Reminder alerts (instead of current 5 minute intervals).
? Message option in action menu for Notes.app.
? Swipe to right gesture for Notes.app list like Mail.app on iPad.
? Forward/Back gesture for Safari on iPad like OS X Lion.
? AirPlay support app-wide in voice Memos.
? Move settings for Game Center to pane in Settings.app instead of under "Account" section.
? Ability to remove games directly from within Game center.app.
? Add "Favorites" section to Friends section of Game Center.app in place of "Recents" tab.
? Expanded feature set for YouTube app.
? Page swipe animation in Contacts.app on iPad like in Calendar.
? Option to hide undownloaded music videos from Videos.app just like with music when using ITunes Match.
? Provide short tone while on a call for notifications instead of playing tone through ringer and vibrating in ear. So annoying.
? iCloud sync for ringtones and alert tones.
? Optimize the shutdown spinner for the Retina Display
? System-wide ability to dismiss the keyboard on iPhone with gesture in Messages.app.
? Ability to one-tap call contacts from Spotlight via toggle in Settings.
? Speed up the purchased sections of the App Store, iTunes Store, and iBooks Store. They're way too slow to use...
? iPad: Show pic count for albums (next to titles).
? Better differentiation/contrast between button states for Shuffle, AirPlay, etc. in iPad Music Player.
? "Download Album" button on left column under each album cover when sorted by artist, "Download All" button moved to upper right corner, in line with artist, and make the left column with album artwork is touch sensitive for scrolling.
? Proper alignment and spacing between all interface elements in iPad Music Player.
? End repeat "after __ number of times" in addition to "on a date" in Calendar.
? Global toggle for Notifications.
? Sync Bookmarks and Recent Locations for Maps.
? Unify scrubber popup for dates in Calendar and Reminders, and time in Voice Memos.
? Unify button (Store, Edit, etc.) placement in iBooks between iPhone and iPad as well as unify "Edit" controls between iBooks and iWork apps.
? Real-time swipe animation in iBooks akin to Lion desktop switching. Bookshelf switching displays this animation upon swipe.
So, all that ^ among many other little graphical fixes and tweaks would make me happy! haha
I suppose these aren't all out of the question as I would consider some bugs and most are very small tweaks or fixes. Just this stuff would be my dream iOS 5.2.