I tried to execute specific plugging right after clean up i.e. post-clean (default is clean phase). This worked for me with eclipse indigo. Just added post-clean resolved the problem for me.
<executions>
<execution>
<configuration>
</configuration>
<phase>post-clean</phase>
<goals>
<goal>update-widgetset</goal>
</goals>
</execution>
</executions>