Those are the Nikon mount lenses Sigma has released this month:
18-125mm F3.8-5.6 DC OS HSM for Nikon Release Date 2008.6.20
APO 150-500mm F5-6.3 DG OS HSM for Nikon Release Date 2008.6.18
APO 120-400mm F4.5-5.6 DG OS HSM for Nikon Release Date 2008.6.11
I believe those are Japan’s release dates, since they are not yet available on the US web site.
Source: Sigma Japan