We don't yet have a lightweight wallet available. However MultiChain is largely compatible with bitcoin wallets, except from the handshaking when two nodes connect. We're hoping that the next alpha will enable pure bitcoin-style handshaking between nodes for chains where anyone-can-connect is true, i.e. where the permission to connect is not restricted. This will make existing lightweight bitcoin wallets compatible with MultiChain, although of course they will need to be updated to display and send assets other than the chain's native currency.