Few days ago PhotoRumors broke the news about a new upcoming announcement from Sigma. The details are now in: on Thursday Sigma will announce a new free mount conversion service. This will allow switching between brands very easy and will bring an extra incentive to buy Sigma lenses.
Sigma is getting very serious with their recent announcements and future plans (rumors about a new 24-70mm f/2 OS HSM lens) and it will be interesting to see how Nikon will respond.
Update: the mount replacement service might be free, but you will still have to pay for the shipping and handling to Japan.
