Thomson-Reuters calculates the de-facto "official" impact factors, but their interface does not give search capability specifically for "bioinformatics". Using some of their other categories, you can see some of the main ones:
If your University pays for a subscription to Thomson Reuters Journal Citation Support service, you should be able to get someone there to pull that information for you (usually your Library can do it). Thomson and Reuters does not make that information available to the public without a fee.
Thomson-Reuters calculates the de-facto "official" impact factors, but their interface does not give search capability specifically for "bioinformatics". Using some of their other categories, you can see some of the main ones: