We tell people that a good way and good reason to use a press release is in reaction to a very important event within the company, if you are a VIB (Very Important Brand). EX: BP in response to the Gulf oil spill. It is a way to streamline the talking points for any person representing a brand.

It doesn't have to be a reaction to a negative event. It can be mergers, buy outs, IPOs, big hires. The key is that the people issuing these press releases are VIBs.