I'm sorry, but I agree with the above two comments.

Please don't publish guides that have not been completed - they don't look very good. I would recommend copying your guide, then archiving this one. When you're finished with your guide, with no more "coming soon" chapters, feel free to publish it.

Feedback about the items:

1) Trinity Force: you're getting it way too late with Vayne. As you said, third hit, Tumble + Sheen prc = huge damage. Ie, Sheen should be an early game item.

2) You call Vayne squishy, and then all you buy is a Frozen Mallet, which is a questionable buy, considering you also buy Trinity Force. Wouldn't Banshee's Veil or guardian's angel be better items than Frozen Mallet?

I would also look up how to utilise BBC Code. Your guide has no images and is very bulky. Also, don't include champion history to beef up your guide. It really looks bad :/

The item build is off as the above post says, your masteries are off ad your rune choices are questionable, also you put coming soon for the majority of your guide which would otherwise give your reasoning for your choices, I'm sorry but it needs a lot of work.

A couple things i dont like about this build, and please take this as constructive criticism and not me bashing your build.

First off I simply dont understand why you would grab a gunblade over a bloodthirster, vayne uses all AD and no AP, and the AD with the lifesteal is far superior then a gunblade. Plus you dont even need the active from the gunblade for the slow, you grabbed trinity and frozen mallet.

Second: your mastery tree is mixxed and isnt built into one tree, so unless your just trying to go more survaibility and not a carry, then i would definately go with 21/9/0

Third: is ghost really viable here? you have trinity, phantom dancer, berserker greaves, and not to mention your passive and ultimate. unless this is purely to be used as an escape mechanism why take it? you have flash that should be your escape route not ghost. you should grab exhaust instead for those annoying champs trying to get away early game.

good start i guess, but just some food for thought

link to my Vayne build:
http://www.mobafire.com/league-of-legends/build/vayne-the-ultimate-chaser-84904