I've done this. Not for sneaky/malicious purposes but just to provide a better experience. Also batching features around adding permissions, I'd rather release one update with two new permissions than two different updates each requesting a new permission.
Nova Launcher has had the "Set Wallpaper" permission from the start, most launchers have it and use it, but Nova didn't actually needed it initially as the set wallpaper functionality was just calling other apps that held the permission themselves. But I knew Nova would at some point require it (and indeed it does now) and users completely expect the launcher to be able to set the wallpaper, but users still get confused or annoyed by the new permission screen.
"Google Play License Check" is another permission I've requested but not used. It's a reasonable permission for a paid app to have and not one that users email me asking about, but when I first added it to WidgetLocker I did get users asking about new permissions (The "Android Market" at that time didn't specifically point out which permissions were new, so people would just ask about any permission they didn't realize the app had all along). In a future update I ended up disabling license checking because it was proving to be more trouble than it was worth, but I didn't remove the permission because if I ever wanted to turn it back on I didn't want users to be prompted about the permission again.
Requesting something like Read Contacts without actually using it would probably upset users, as some will ask about those kinds of permissions and expect a reasonable answer. Saying it's just for future use would seem a bit suspicious.
