Most IT guys have no problem with a Apple device, on it's own. However, it's not just a question of plugging it in to a corporate network.
There's a whole bunch of management behind the computer system that "creative types" don't see. Each new environment has real money costs way beyond the purchase price of the kit.
Just off the top of my head (and i'm not an expert on Apple Desktop Environments):
You need someone with support skills to manage the environment. You need tools to manage the mac, and ensure compliance with corporate policy. These tools probably don't integrate with what is currently implemented. There may be the hidden costs of potentially incompatible document formats (Office Documents), different feature sets on web browsers. The anti-virus software probably doesn't have a Mac version, so requires a one off purchase.
True story: Createive type got approval to buy a mac at one of our regional sites, via the wrong budget. Bought all MS Office and software and installed it herself. Outlook is essential to her work (and in this case, REALLY essential). Of course, not having cleared the purchase with IT, she didn't know that the current version of Outlook doesn't integrate natively with Exchange 2003. (Yes, I know IMAP works).
The "creative types" need to sit down and talk with IT. Not at IT. IT need to listen and understand the requirements. Creative Types need to wear ther cost of supporting a second discrete infrastructure.
Where did I read about "Infrastructure: The stuff everybody needs, but no one want to pay for"? Probably Dilbert.