The Foundry USA Pool has launched a page detailing BIP-110 and is inviting clients to vote on the initiative via an email form. BIP-110 proposes a soft fork that restricts arbitrary non-monetary data in blockchain transactions, including limits for the OP_RETURN field and other information transfer channels. The voting window will close at block #961,632 (approximately early August).
According to the Hashrate Index, Foundry holds over 22% of Bitcoin's hash rate.