angiolo - 12:57 pm on Mar 6, 2006 (gmt 0)

> Lack of inbound links is probably one factor.

Not for me.

I monitor several sites. Few of them got supplemental.

What does exactly it means "got supplemental"?

It means that on about half of the Google DBs ( the Big Daddy databases ) only the index page had been indexed... Most of other pages got supplemental despite the fact that the supplemental pages had been cached this february.

Had the sites been penalized?

Not for the home page! They rank fine as usual for the most important keywords...
They lost about 10 % in traffic.

They lost some traffic from the supplemental pages for subsidary keywords.

Does Googlebot visit the sites? Yes, daily!

Is there any reason for reaching the supplemental Club?

NOT A COMMON REASON!

- All of them have a good page rank ( Minimum 6 )
- No Black hat or tricks or fake link campaign
- Two sites are gaining link popularity in a natural way (excellent content: they do not need any link campaign)
- One site did not do anything in the last two years!
- None of them display Adsense

Three of them changed hosting during the last two years: this is the only "partial" common factor.

I think that, as GoogleGuy said, it's a temporary glitch...