Michael:
I think you are looking for the 'busy' child element of snapshot-info.
$MStatus = $ss->child_get_string("busy");
The raw results back from ONTAP look like this:
<snapshot-info>
<name>hourly.0</name>
<access-time>1297717253</access-time>
<total>2836</total>
<cumulative-total>2836</cumulative-total>
<dependency/>
<busy>false</busy>
<cumulative-percentage-of-used-blocks>0</cumulative-percentage-of-used-blocks>
<percentage-of-used-blocks>0</percentage-of-used-blocks>
<cumulative-percentage-of-total-blocks>0</cumulative-percentage-of-total-blocks>
<percentage-of-total-blocks>0</percentage-of-total-blocks>
</snapshot-info>
-ryan