<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>forma</class>
 <widget class="QMainWindow" name="forma">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QComboBox" name="comboBox">
    <property name="geometry">
     <rect>
      <x>70</x>
      <y>110</y>
      <width>651</width>
      <height>22</height>
     </rect>
    </property>
   </widget>
   <widget class="QLabel" name="label">
    <property name="geometry">
     <rect>
      <x>285</x>
      <y>190</y>
      <width>191</width>
      <height>20</height>
     </rect>
    </property>
    <property name="text">
     <string>TextLabel</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton">
    <property name="geometry">
     <rect>
      <x>350</x>
      <y>370</y>
      <width>75</width>
      <height>23</height>
     </rect>
    </property>
    <property name="text">
     <string>PushButton</string>
    </property>
   </widget>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

from PyQt4 import QtCore, QtGui, uic
import sys

def byaka():
    form.label.setText(form.comboBox.currentText())
    #form.label.setText("Я злой как чёрт!")

app = QtGui.QApplication(sys.argv)
form = uic.loadUi("gadost.ui")

kaka = ["one", "two", "three", "four"]
for i in kaka:
    form.comboBox.addItem(i)

QtCore.QObject.connect(form.comboBox, QtCore.SIGNAL("currentIndexChanged()"), byaka)
QtCore.QObject.connect(form.pushButton, QtCore.SIGNAL("clicked()"), byaka)

form.show()
sys.exit(app.exec_())

form.comboBox.currentIndexChanged[int].connect(byaka)
form.pushButton.clicked.connect(byaka)