Starwood Preferred Guest - Starwood Elite Tiers

Sorry for the newbie question here...

On the SPG site, I see mention of 3 tiers for the frequent stay program:
- Preferred Guest. Basic level, no special benefits
- Gold Preferred. Upgrades, more points, etc
- Platinum Preferred. Better upgrades, etc

In the discussions here, I've seen talk of a Preferred Plus level (between Preferred & Gold). This comes for AAA members, promos, and Starwood Amex holders.

Today when I visited the SPG site, I noticed I'm a "Preferred Business Guest". I haven't really looked before today... Anyone know what that might mean? Any special benefits?

Thanks,
Extra

Preferred Business Guest is Preferred Plus.

For more information on Preferred Plus:
http://www.flyertalk.com/forum/showthread.php?t=421462&highlight=preferred+business

Thank you very much - that was what I was after.