How can I get a list of all incoming connections to a node?

Update: This is a perfect example of overengineering ;) I did all the below work before I realized there is a listHistory node, which does all this for you. Check it out...

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Say you have a list of Maya materials, and you want to find all the place2dTexture nodes connected to them.

# Python code
import maya.cmds as mc
def allIncomingConnections(nodes, nodeType=None):
    """
    Based on the nodes, find all incoming connections, and return them.
    This will recursively search through all incoming connections of all inputs.
    
    nodes : string or list : of nodes to find all incoming connections on.
    
    nodeType : None, string, list : Optional, will filter the result by these
       types of nodes.
    
    return : list : Nodes found
    """
    ret = []
    
    # Convert our args to lists if they were passed in as strings:
    if type(nodes) == type(""):
        nodes = [nodes]    
    if nodeType is not None:
        if type(nodeType) == type(""):
            nodeType = [nodeType]
            
    for n in nodes:
        incoming = mc.listConnections(n, source=True, destination=False)
        if incoming is not None:
            for i in incoming:
                if nodeType is not None:
                    if mc.objectType(i) in nodeType:
                        ret.append(i)
                else:
                    ret.append(i)
                nodes.append(i)
                
    # remove dupes:
    ret = list(set(ret))
    return ret

Example:

incoming = allIncomingConnections("myMaterial", "place2dTexture")
print incoming
# [u'place2dTexture643', u'place2dTexture642', u'place2dTexture641']