First-order effects

• If Facebook ships a true location feature within weeks as reported, its full member base gets check-in-style sharing natively, and Foursquare and Twitter each face the same question overnight: is their location layer a product or a feature someone else now bundles.
• The report says Facebook is lining up outside partners for the launch — whichever companies make that cut inherit distribution no standalone check-in app can match.

Second-order effects

• Foursquare and other dedicated check-in services are pushed toward either deeper utility or partnership deals with the platforms rather than competing on raw check-in mechanics.
• Per AdAge, brands are the stated second wave — a location feature wired into Facebook's graph hands advertisers a local targeting surface that pure-play check-in networks were positioning to sell first.

Third-order effects

• If the pattern holds — big platforms absorbing standalone mobile features once they prove demand — location shifts from a category of independent apps to a checkbox inside incumbent social graphs, forcing the independents to sell data, partnerships, or niche depth to survive.
• A Facebook-scale entry into location also raises the privacy stakes for the whole check-in space: whatever defaults Facebook chooses become the de facto norm users expect everywhere else.