No. I use my Jailbroke iPhone an an exchange server and there are no issues. Jailbreaking does not take away any functionality of the iPhone. It allows you to add new functionality, but it at the cost if the oem features you like. So go for it!
However, keep in mind that since you used a "vulnerability" to jailbreak your phone that "technically" your phone would be succeptable to being "hacked" and your information taken....
AWW HECK WHO THE F AM I KIDDING....JAILBREAK IT!!!