It appears that at least one of the four co-op modes in Splinter Cell Conviction's 4 player co-op Deniable Ops mode will be available to pre-orders only for the time being. Amazon's listing for Splinter Cell Conviction lists Infiltration as a pre-order bonus.
Get a code to unlock one of four co-op modes, the Infiltration mode, and lay the groundwork for co-op domination on day 1.;
The wording makes it sound similar to what EA did with Army of Two: The 40th Day and its Extraction mode. This also appears to be a Amazon exclusive, as Gamestop lists a shotgun and access to Ghost Recon: Future Soldier's beta as pre-order bonuses.
Thankfully the incredible looking co-op campaign is still included without plunking down your hard earned cash early. We'll update you as soon as we have more info as to when exactly Infiltration will be unlocked for everyone.