This is all a matter of opinion, and will depend on your particular business or service. If you believe the benefit will outweigh the security risks (phising sites, spam, etc.) and take the time to dedicate to its use, then by all means, make it work. If you do not believe it will be worth your time, move on to another social networking option.
Overall, it is not tremendously beneficial to a business, though small businesses in need of a local target audience will probably see a greater benefit, because of the connections.
The recent launch of a promotional program similar to Google AdSense may change the face of MySpace for business, but with the program still in beta, it's hard to say.