At Launch, there will be two ways to aquire MPL tokens First, liquidity providers will be able to earn MPL rewards by providing liquidity to the network. Second, a Balancer Liquidity Bootstrapping Pool will be seeded with MPL tokens. Balancer LBP's have gained popularity as a fair mechanism for launching a token. LBP pools are designed to avoid front running- they generally start at a high initial price and fall over time as participants are incentivized to wait until the price falls.
Details on acquiring MPL will be announced closer to launch.