Will backing up to iCloud still work if I jailbreak my 4s? Will anything be backed up that I don't want to be backed up? Will restore from iCloud still work after a jailbreak?
iCloud backup still works but doesn't backup any jailbreak tweaks. Also I jailbreak my phone yesterday right after released and iCloud said it backup at 1:30am so that still work.
iCloud will work exactly as it did before. There is just one thing to consider when backing up a jailbroken device - the backups will contain scraps of jailbreak data. You'll still be able to use the "contaminated" backup when you restore with no problem. The only downside is that the backup (and any resulting restores) will increase in size by several MB (depending on what tweaks you have).