See: "http://www.internetweek.com/enterprise/enterprise121701-1.htm";
"... The operating system's growing popularity is an indication that IT managers are becoming more confident in Linux's viability as an alternative to other commercial operating platforms, albeit gradually. Perhaps the most notable area where Linux is poised to gain enterprise credibility is on IBM mainframes, where Big Blue's newest software and hardware offerings let companies run Linux partitions. ... "
