From Zencash webpage and forum:
There is nothing happening at block 100,000.
https://blog.zencash.iohttps://bitcointalk.org/index.php?topic=1819977.240Zen Launches During Consensus NYC on May 23
Zen will launch as a fork of ZClassic. Inspired by Ethereum Classic’s fork from Ethereum, all existing ZClassic holders will receive an equal amount of Zen at launch. This is a demonstration of the support of the community for both coins going forward. The Zen team is working with select Exchanges to assist in this process, and will announce the specific ways to make sure Zen coins are awarded 1-for-1 with existing ZClassic.
Zen launches on Tuesday, May 23nd at 10 pm Eastern. By that time there will be many other elements of the launch in place. This includes:
Verified exchange support
Linux wallet and roadmap for other wallets
Node specifications and configuration instructions
Mining pool applications
This is an exciting time! Bitcoin has shown everyone what is possible with cryptocurrency, Zcash developed truly secure transactions, Dash demonstrated how developers and node operators should be rewarded with funding along with the miners, Decred showed a sustainable model for governance.
Zen is a truly revolutionary platform that takes the best from other crypto-currencies and adds secure communications, secure resilient nodes, and a governance organization to enable continued improvement forever!
If you would like to be part of the Zen movement, come find out more and become part of the community at zencash.io.
Can I invest in Zen prior to launch?
Yes. Anyone who holds Zclassic prior to the launch on May 23rd will be given a 1:1 credit of Zen. This is a result of the Zen genesis originating from the Zclassic blockchain.
I am an early Zclassic investor, what does this mean to me?
Anyone who holds Zclassic prior to the launch on May 23rd, 2017 will be allocated a 1:1 amount of Zen automatically. Simply import your private keys into the new Zen wallet to redeem your tokens. We are also working with the various exchanges to ensure everyone will be credited appropriately on their platforms.