The "IT genius" is sometimes a strange duck, even within IT. This person can be your most productive worker, or your least productive. Frequently even more of a loner than most IT workers, s/he may require the freedom to explore new vistas and yet can sometimes need guidance to stay on track on with timelines and project deliverables.
If your departmental guidelines do not absolutely require that programs be written using a particular language (COBOL, c, C++, etc), your "IT Genius" may be able to use another language to develop the same program more quickly and with more efficient processing... just keep track of the progress s/he is making. Another good idea: have someone NOT familiar with the program provide a "peer review" of the resulting source code. These "IT Genius" types are notorious for poorly documented source code because their minds think too far ahead about what the program will be doing next. If the reviewer cannot understand the program flow, allow the reviewer to work with the developer to add the necessary comments.
Managing the "IT genius" does not mean that you should never hold him/her responsible for progress. The same personality traits that will drive this worker to research a more effective way of processing can cause the worker to veer off on a "rabbit track" and lose track of time. The internet search to find out how to access a file in PERL can lead to a side trip into how to use the PRINTF statement in AWK. This may be a perfectly natural extension of a further need in the resulting UNIX script being worked on, but it could also be an "unnecessary" trip to learn something new. The IT "genius" frequently has an almost insatiable desire to learn, which is why s/he has such an expansive knowledge base.
If you have an "IT genius" on your staff, you probably feel either blessed or cursed, or sometimes both at once. These people can often be difficult to befriend; they can be petulant if they feel they've been slighted; and they can sometimes be considered "uppety" because they forget that others do not have the same drive to learn. Involving the entire team in meetings, breaks, etc can sometimes overcome this limitation, but it may require work on your part as the manager to draw this person into the conversation, but the benefits can be worthwhile.