But there's no great support for music, movie/tv, or podcast content that way.
Sure there is. iTunes + iTunes match is the best music in the cloud implementation out there. Movies and TV shows work fine as long as you bought them from iTunes (problem with non iTunes video of course is the studios).
Being able to check off a box on the iCloud feature chart ("Movies!", "Photos!") is not the same as having a viable syncing feature.
Movies and TV shows are "available" as previous purchases in different devices and iTunes instances, but they have to be manually managed, downloaded and deleted as necessary. No metadata is preserved (it's like re-purchasing the thing). Plus "as long as you bought them from iTunes" is a big asterisk.
The music situation is much better with iTunes Match, but: i) iTunes is free, while iTunes Match is not; ii) iTunes Match has various limitations -- for example, half of my smart playlists won't sync, and the workaround is a lot of tedious manually tagging of tracks and redefinitions of my playlists.
Photo Stream, which the GP mentioned, is barely usable as a photo library. It's not supposed to be. Rather, it's just a way to shuffle the files around, until you can get them into your real library.
Similar limitations apply to addresses, probably others...
The common theme here is that they're trying the best they can to make the content available, but they're not so good at preserving libraries. It should be cheap for Apple (and free for users) to sync library metadata with perfect fidelity across all devices. The separate question of how to find the content -- whether it's stored locally, or on the LAN, or in the cloud -- that's where the real storage costs are, and where Apple should offer its services as one alternative (and try out innovative optimizations like Photo Stream and iTunes Match). Some people will want to pay for everywhere access to all their home videos; others will be happy with a "sorry, that's not available here" message on the road, while being able to play them at home over WiFi.