What is the new glitch?
The new glitch lets you get "Storage" without Forest Water. Storage isn't new, but now you can get it anywhere just by cancelling Wind Waker from a Wind Waker Dive just before hitting the ground. This means super swimming and more skips (Boss Key skips, easier Cabana Deed Skip, etc.) are possible.
Video: http://www.youtube.com/watch?v=aSVOFHMK-cU

What is "Double Storage"?
Double storage is how you get storage AND camera lock at the same time. It is achieved by getting storage while text is on screen from text storage (by pulling the Wind Waker). It allows you to superswim through a cutscene (by storing the cutscene).

What is Wind Waker Dive?
Using the Wind Waker just before you start falling of a ledge makes Link fall while in "playing with the wind waker!!" mode. In order to WW Dive off of any ledge that isn't a slope, you need to have a bomb, pot, skull, nut, etc. to push you off. Glitchesandstuff has found some "easy setups" to perform dry storage without a full Wind Waker Dive by climbing onto ledges that push you off.
http://www.youtube.com/watch?v=OB9bUZFziq8
http://www.youtube.com/watch?v=H7oIml4dLZA

What does storage do?
All information (the "How To" is outdated) is here: http://zeldaspeedruns.com/tww/Techniques/storage
Text Storage - store text and then the next thing you speak to reads the stored text
Chest Storage - let's you partially clip into walls because you are stored in "collecting an item!" mode (combined with text storage so everything isn't dark) - leads to boss key skips and the cabana deed skip
Door Storage - can make link walk to silly places and mess up the loading of rooms
Scene Interruption - you can walk around during a scene or even delete it (making the game impossible to complete)
Camera Lock - the camera gets stuck if an item is used that changes it to a fixed position (like wind waker). This lets you super swim!
... and more!
http://zeldaspeedruns.com/tww/Techniques/storage

How do you get bombs early?
In order to get bombs early Link needs to land on Great Fish Island from a Super Swim without triggering the cutscene and then pull out the wind waker in order to fix the camera (so the game doesn't soft lock). It's very tricky, but it has been done on console!

What is super swim?
If you get "Camera Lock" with "Storage," you can enter water and hold up to super swim. This works because backwards speed isn't capped in the game (like backwards long jumping in Super Mario 64). This was previously only useful for TASes using a different method, but now it is doable several times in realtime runs since players aren't limited by Forest Water expiration.

How much time does it save?
Routing is still being done. It seems this will only save time before Ballad of the Gales (BOTG) is learned. BOTG lets you warp around the map with the boat and every big key door after that already has a fast skip. Also, the grapple hook (and the boat) are needed to pick up Triforce charts from the ocean floor. Sub 4:50 is definitely possible.

Who discovered this glitch?
ForgoneMoose (a new TWW speedrunner) PMed Cosmo saying he managed to get Camera Lock (because of storage) without Forest Water from a failed WW dive attempt. After a bunch of testing, him and abahbob were able to figure it out.
Abahbob's YouTube: http://www.youtube.com/user/abahbob

Can this let you skip the barrier? Barrier skip!!!
Not yet. The same problems that existed before still exist (no door in that area). Barrier Skip is the theory of getting to Ganon's Tower without breaking down the Hyrule Barrier.
http://zeldaspeedruns.com/tww/Miscellaneous/barrier-skip

Boss Key Skip examples:
Forbidden Woods - http://www.youtube.com/watch?v=8HHcpefLP44
Dragon Roost Cavern - http://www.youtube.com/watch?v=Rsj1ED3kreM

Helpful links:
http://zeldaspeedruns.com/tww/
http://www.youtube.com/user/Glitches0and0stuff
http://www.youtube.com/user/cosmospeedruns
http://www.youtube.com/user/abahbob