In an enterprise environment, it isn't practical or sane to "instantly" provide speech recognition to everyone at once. Instead, you must choose who will benefit most, tempered with judgement regarding who should be the leaders in adopting the new technology.
First, deploy speech recognition in the obvious cases where a person has physical problems using the keyboard. Take the initiative and ASK those who use a keyboard more than a few minutes per day -- in a large organization, you will find good corporate citizens who haven't complained that their hand/arm/wrist/elbow hurts every time they have to use the keyboard. These people may be eventually lost to disability leave, at great expense to your enterprise, if you don't help them.
At least one Information Services person needs to use speech recognition. They may tell you that they don't write much-- turn off their e-mail and see how many minutes go by before they complain that they can't respond! One simply can't support this technology well unless one uses it some of the time.
Next, deploy to the computer-literate personnel who have to produce documentation but who have no clerical support for doing so. Among these you will find persons with poor typing skills. Often these people have excellent verbal skills. These people know their limitations -- an open invitation to "see" speech recognition will bring these non-typists out in force. The economic benefits can be great: a 10 wpm "non-typist" writing 2 pages per day spends about an hour at the keyboard. If this time is cut to 15 minutes per day with NaturallySpeaking, a computer upgrade, and about 2 hours of training, you'll have a return on investment so great that you'll have to tone down the numbers to make it believable. (If you are in a company with perfect management, you won't have any such cases because no one has been allowed to be so inefficient :-) )
Use the above persons to help establish vocabularies, identify phrases common to your organization, etc. If using the Professional products, exporting vocabularies from these users to other new users with similar vocabulary needs will reduce the time the new users spend on adding words and phrases. At this stage, consider concentrating efforts on a particular group within a company where vocabulary needs are similar. Decide whether a custom vocabulary for the company/division would be worthwhile.
Next, address those that produce lots of documentation per day by handwriting and then passing off the typing to another person. Some of these people have few computer skills -- do not underestimate the need for time to learn basic computer skills.
By the time the above cases are handled, most organizations will have a set of people who WANT the technology on their desk. Take care of these people next.
Persons doing data entry often benefit from having macros, commands, and other shortcuts built so they can efficiently use speech input. Plan on a slower roll-out of the technology with these persons, making sure that a couple of persons are productive before deploying it to a whole group.
Learn to distribute vocabulary and commands using the Data Distribution tool, presuming you have the Professional or Medical or Legal versions of NaturallySpeaking. The Preferred Edition lacks features for sharing macros/commands/vocabularies and is not recommended for enterprise deployments.
Last, handle the 100+ wpm typists without physical problems, persons who don't write more than a few words per day, etc. The economics of speech recognition aren't great for these persons -- yet.
Watch out for those who don't talk clearly. Hire a local speech/drama teacher to spend an hour or two teaching better speech habits. If funds are really limited, find a struggling actor -- they work cheaply :-) If you are planning a roll-out of this technology and you are REALLY smart, you'll have that instruction done before the rumor mill tells people that their computers will start listening.
Also avoid those who think that once the microphone is attached to their system, the company will be able to hear EVERYTHING that they say in their office. Those who think the company is spying on them are not good candidates for speech recognition.
Remember, you aren't in the business of deploying speech recognition -- keep your own business needs in mind. If you sell Christmas trees, don't try to roll this out during December. If you are an accounting firm, March/April is not a good time to deploy this!