I don't know how Tamron has done it, but they made a great thing even better. There's a 'new' version of the 18-270mm Super Zoom lens. This lens might hold the record of longest zoom in a single lens, and this all includes Image Stabilization or as Tamron puts it VC - Vibration Compensation. I admit Tamron's VC is very very effective and much quieter than most of my Canon IS lenses.
This is a highly recommended lens by me when i'm looking to travel light on vacations. I get the best wide and super duper zoom features in a single lens (NOTE: not for full frame cameras). Below is a snapshot of my 60D with the original version of the Tamron 18-270mm.
So what's great about the new version? New motors make the lens more silent and faster. Smaller too. Yes, as if they couldn't make a 270mm Lens any smaller, they've managed to cut down the whole package another 24%. Obviously this all translates to being even lighter than the original version too. I know, you're curious about Video quality. I loaned my original version out to a friend and had a hard time getting it back, he loved it so much. Here's a sample video below shot during his trip to China on the 'older' 18-270mm @24fps.
The Video above is a good example of how far this lens zooms out to, so that you can grab a few 'stolen shots' or use it for 'stealthy street photography' without your subjects even knowing. Now you're wondering about Photography. What is the difference in zoom from 18-270mm? Here's two examples I shot in a Museum, one at 18mm on a Canon 7D and the other at 270mm (handheld too - love the VC).
Overall this lens won't give you the most incredible shallow DOF as a single Prime lens would, but once you have it in your hands, it's hard to let go. The convenience of carrying a single lens with the amount of zoom range and very effective Image Stabilization makes this one of my favorites. And for the first time, this new lens version is now available in a Sony mount (not just Canon / Nikon).