|Don't ask to ask, just ask|
atcroft has it right. I would add one other item - you mentioned:
I had a business development/project manager guy come to my cubicle and ask me for a ‘favor’
Watch out for this. Having people who aren't in your chain of command give you work that negatively impacts your progress on your 'official' work will most likely upset your boss. And when your boss gets upset - well, if you are lucky, he yells at the favor asker, if your aren't lucky, he yells at you.
And what do you get from the 'favor asker'? A heartfelt thanks (maybe) and a reputation as being an IT guy who can handle these little jobs. So they come and ask for help on this new thing they are working on. Worse yet, they tell their friends, who also now come to you. Of course, one of the reasons they are coming to you is that IT has told them that it'll take 6 months before they get their report due to the layoffs, hiring freezes, and not coincidently - the fact that half your time is now spent working on these side issues.
And since Perl is a great tool for these little programs (or not so little programs), the Perl programmer gets the reputation (for good or ill).
One way to handle these things is to make them go through your boss for everything. Say that you're swamped with these other tasks (which you are) and that everything now has to go through him/her. You'll need your boss's agreement (which they should be happy to give, since it gets you back to working on the real work). And it may upset a few, but remember who does your evaluations and determines raises...