Some people who I know are friends of mine at work I have come out to as bisexual. My question is I dont plan on announcing it but is it something I should keep quiet about?
Should implies there is an obligation, so let's see what you might be obligated to do here. Are you required to keep quiet? Are you required to tell anyone you don't want to? The answer to both of those questions is 'no'. You don't have to announce it if you don't want to, perhaps these people felt like it might be a good thing. If you don't, don't bother. If you think it might be good, then that's up to you.
I would say that it really depends on your work environment. If the company is known to be supportive (i.e. has a LGBT network or employee group, has a non-discrimination policy on sexual orientation, etc) then there's absolutely nothing to lose (and a ton to be gained) by being out at work. I'm currently in the state where I know that, but at the same time it's hard. My guess is no one will care, and I know that on a macro level the company is extremely supportive, but on a micro level (the people that you work with day to day), how do you know? And I work at one of the most publicly supportive companies in existence. However, if there are concerns for your job, i.e. you might get fired or something (and you're in a state where that's illegal, actually) then don't broach the topic.
It all depends where you live, work an the mentality of your coworkers. Check your company's policy to see whether they've got an anti-descrimination clause for sexual orientations.
