One of the other cool features of Lightroom is that I can select any photo from my library, add them to a collection and enable mobile sync on the collection. Now any photo I add to the custom collection will sync to all of our mobile devices. Extremely easy.
You can technically sync photo's to iOS from Aperture and iPhoto as well, using Photostream. The difference between Photostream and Lightroom Collections is that Photostream still syncs down the photo to your device (albeit a small version), while Lightroom only syncs a thumbnail. Since majority of the time, users won't actually open all 500 photo's to view on their device, you only need 500 thumbnails. As you can see from my photo above, I have 142 photo's from my wife's iPhone, but it's only using 31mb of storage. When you open a photo to view the full photo, Lightroom downloads the full-resolution for you to see. Much better!
With Aperture/iOS, I could share photo's with my wife through Photostream as well, but my wife would end up saving the photo to her camera roll and a duplicate ultimately ended up in my Aperture library. I would spend a lot of time removing duplicates. Luckily, it seems that Lightroom is smart enough to not import duplicates. Another benefit is that I don't have to manually upload 20 photo's that I just took of my daughter to Photostream for her to see. They just show up in our Lightroom.
If I wanted to have a photostream per device, it made things even more complex. Take a picture on my iPhone, and upload to photostream, then take a picture on my iPad 5 minutes later and manually upload to photostream again. With Lightroom, we can take pictures on any device at any time and not deal with uploading. Lightroom handles it all for us with less effort.
Lightroom calls their version of Tags, Keywords. I downloaded an app on my iPad called Photosmith, that lets you create a collection of photos on your Mac (or Windows) and sync the collection of photo's to your iPad. You can then add keywords, edit the photo's, name them and then sync the changes back to Lightroom. It's a great way to 'tag' photo's while on the go. Until the Lightroom Mobile apps support keywording, I'll use Photosmith to do all my keywording while on the go. It's a bit difficult to set up initially, but in the end it works pretty well.
This process is by far the best photo syncing solution I've found, after several years of messing with trying to take care of syncing to the computers wirelessly and sharing across all devices.