Firefox Sync enables you to share your history, bookmarks, form-fill and tabs opened between multiple computers. The data transfer between two computers is encrypted before being send to Mozilla sync server to be shared.
Panorama is a visual tool with a very user friendly interface which let you organize open tabs into groups. Panorama can be accessed from button on the right of bookmark bar which takes you to your tab playground, where you can expand or delete your tab sets, create new ones and organize them around the canvas as you see fit.
Read more about Firefox 4 Beta 4 at official blog post.