ICANN have just released the results of a 10 month study into domain name front running by security expert Benjamin Edelman that concludes that front running at leading domain registration and domain availability-checking sites does not happen.
I'd be very surprised if I discovered that a reputable company engaged in that type of activity. They would have to intentionally write some software to do this. I suppose that by definition a company ceases to be reputable when they engage in this so no reputable would do this. Didn't Network Solutions do something like this recently? When you searched for a domain name on their site they registered the name so if you then went to another site to buy the domain you were unable to until the five day tasting period elapsed.
I've heard that Apple registers 400 domains at a time when it's researching a new product that might be released to market to attempt to hide the name or intent of the product among a sea of names.