And finally, Minecraft 1.6 - the “Horse Update”, will be released next week! The update has leads, carpets, hard clay, donkeys, mules, and of course horses! This update requires a new Minecraft launcher to load. We’ll post more info about that here and on Mojang.com when it’s ready.

Source of the information is on the Minecraft launcher!

Nice, can't wait for Minecraft 16!
Silly Stevie, learn to punctuate.
Anyways, this is going to be so much fun :D

Sounds Legit


Also This Video Is From May 17th

Because it's a video of one of the snapshots.
Albeit it's one of the earliest snapshots, but it's a good one nevertheless.

I wonder if you can use a sword while on a horse.

Yes, 'twas mentioned in a video I saw (possibly even this one).

I can confirm this.
You can use items whilst on a horse, I.E. eat, swords, bows etc.
Getting onto/into and out of horses, minecarts etc. will now go through shift (Correct me if I'm wrong), so you can block with sword, use a bow etc. without any issues.

Right click to get on, left shift to get off. I think... Tested the snapshot a month ago so I'm not 100% sure.