What is the equivalent NX-OS command for the “ip multicast-routing” IOS command, and does the Nexus 7000 support PIM-Sparse mode?

The command is feature pim. In NX-OS, multicast is enabled only after enabling the PIM or PIM6 feature on each router and then enabling PIM or PIM6 sparse mode on each interface that you want to participate in multicast.

For example:

switch(config)#feature pim
switch(config)#interface Vlan[536]
switch(config-if)#ip pim sparse-mode
See Cisco Nexus 7000 Series NX-OS Multicast Routing Configuration Guide, Release 5.xfor a complete configuration guide.