If someone asks me this, then I'll find out the background experience that person has. A mainframe expert like you would be proficient in dealing with batch centric jobs. As Ranganathan put it, SAAS has a broad meaning.
In my opinion, mapreduce and big data management has got more in common with mainframe people than cloud centric environment.
Gartner says :Bigdata will be most advanced analytics products by 2015 !
Time to Become Big data architect by learning Hadoop(Developer,
Mahout, Splunk,R etc) from scratch to expert level