Yes - and twenty years ago, those owning the accounts payable system were fiercely guarding it against those who owned the general ledger system. Payroll and HR were two different silos as well. ERP systems put an end to that and compelled integration on common platforms. It's IT's turn now. The real question: standards or proprietary?
There's ROI here in reducing complexity and enabling cross-functional process, and I'll bet on the ROI over the politics.
It seems to me, that integating back end systems is a high priority for most CIOs. This article outlines the big picture of hardware and software integration efforts so far: http://www.cioupdate.com/trends/article.php/3307401. The effort as of late includes ERP systems in particular ... especially since the passage of Sarbanes-Oxley.
Getting rid of all the silos and gaining a single view into the infrastructure seems to be one of those holy grail goals for most CIOs. Otherwise, they are stuck supporting and maintaining 100s of disparate apps. and infrastructures that don't interoperate, or if they do, require extensive programming and baby sitting to make work correctly.
It's been such a long time since, and bumping into this discussion while searching for today's systems worth adding a little time-line.
My point is that most open-source solutions are growing at a rate that is too fast for proprietary providers to cope with. Some analysts even say there are open-source erp's that provide more then traditional providers, in terms of capabilities and speed.
Based on Sourceforge reports, today's most used is Openbravo.