gistfile1.txt

In [1]: import jsonpath

In [5]: foo = {'payload': {
        u'metrics': [
            {'timestamp': u'2013-07-29T06:51:34.472416',
             'name': 'cpu.frequency', 'value': 1600,
             'source': 'libvirt.LibvirtDriver'},
            {'timestamp': u'2013-07-29T06:51:34.472416',
             'name': 'cpu.user.time', 'value': 17421440000000,
             'source': 'libvirt.LibvirtDriver'},]}}

In [11]: jsonpath.jsonpath(foo, 'payload.metrics.[?(@.name == "cpu.frequency")]')
Out[11]: 
[{'name': 'cpu.frequency',
  'source': 'libvirt.LibvirtDriver',
  'timestamp': u'2013-07-29T06:51:34.472416',
  'value': 1600}]

In [12]: jsonpath.jsonpath(foo, 'payload.metrics.[?(@.name == "cpu.frequency")].value')
Out[12]: [1600]