GR:FS has been announced for PC, the release date is TBC, but will be after the console versions. We expect to have more information about the PC version once the beta for the consoles has started.
We have no information about a Steam version, if or when an announcement for Steam is available we will be sure to post it in the forums. You should also keep an eye on http://ghost-recon.ubi.com/gr-portal/en-GB/home/index.aspx for news and updates.
Pre-order details are here http://ghost-recon.ubi.com/gr-portal/en-GB/pre-order/index.aspx
PC page here http://shop.ubi.com/store/ubiemea/en...ctID.246429900
To answer Cowboy_6686's question, yes that is the Signature Edition.