Segwit is finally activated. Bitcoin blocks can now be up to 4 MB, though 2 MB is a more realistic maximum.
However, this doesn’t mean that all blocks will immediately bump to 2 megabytes in size today. For a transaction to utilize the added space, it must be sent from a SegWit address (or more accurately, a Segwit “output”) — not just to a SegWit address.
Wallets and other applications need to be ready to accept SegWit transactions.
Some wallets, like GreenAddress, may offer this option on day one, or shortly thereafter. Similarly, large Bitcoin service providers could start accepting SegWit transactions right away, though some may need more time to prepare. BitGo, a Bitcoin infrastructure provider for major exchanges like Bitstamp, Kraken and OKCoin, expects to be SegWit-ready relatively soon as well.
https://bitcoincore.org/en/segwit_adoption/Lightning and other implementations.
Arguably even more highly anticipated than an increased block size, second-layer technologies like the Lightning Network or, further out, Merkelized Abstract Syntax Trees (MAST), will be more easily built on top of Bitcoin. Most of this technology is still a work in progress, and it could take several more months before regular users are expected to use it. That said, it is likely that there will be experimentation on Bitcoin’s mainnet rather soon.
Version 0.3 alpha of Lightning Network Daemon software was released yesterday, which is the last major release before mainnet beta release.
And even when the Lightning Network is functional and in use, it will take a little longer to roll out more advanced features that utilize the Lightning Network or similar protocols. These include atomic swaps, which allows for the instant and (near) costless exchange of cryptocurrencies over different blockchains, like bitcoin and litecoin.
Further, more nuanced benefits of SegWit, such as faster transaction signing by hardware wallets, will be available within a matter of days.
https://bitcoinmagazine.com/articles/segregated-witness-activates-bitcoin-what-expect/