Welcome CLG. I have disclosed about my illness at work and certainly this is a decision a person shouldn't take lightly. There are pros and cons of it, but in doing this I can say the only people that truly understand it is one of my friends/co-workers who has been diagnosed with depression and another co-worker that has bipolar. What I would like from friends/family would be some empathy, but in all honesty that's in short supply.
I don't get any extra slack at work and I don't think I would want to be treated any differently. I may have bipolar, but I'm an excellent employee and an asset to my organization.
As far as climbing the corporate ladder I'm at peace with not striving for that anymore. This isn't to say a person with BP doesn't excel in high profile/stressful careers, I actually think it's the opposite and there are many persons with BP that are entrepreneurs, lawyers, doctors etc. but for me it's more important to have work/life balance. I also really like the career I have now (I'm an Inspector with the Gaming and Liquor Commission) and it's a good fit for me.