It is indeed in the beta.
In the Photos app there is now an Albums area where you can add new albums.
You hit an Edit button in the upper right corner, click Add to add a new album, and then you can select pics to add to it (if you want; you don't have to add pics to the album right away).
You can associate pics to an album (notice: not move or copy; see below) from the Camera Roll by going to the Camera Roll, hitting that little "share" button in the bottom left (the same button we use for selecting pics to delete), selecting the photos and then hitting the "Add To" button at the bottom. You can add the pics to a new album or an existing one. Note that the pics are not moved or copied from the Camera Roll to the album -- they are merely associated with that album. You can associate pics between albums in the same way.
Pics are not copied byte-wise between albums and the Camera Roll, but rather the albums contain references to the pics in the Camera Roll. This is evidenced by the fact that when you remove a pic from the Camera Roll, it is also removed from any albums it may be associated with. So the Camera Roll is essentially your library with the albums being the means to organize them.
