When Facebook first announced that there would be big changes to the Platform back in October, many developers instantly grew concerned about the implications of notifications being completely removed. Within days, Facebook calmed developers’ nerves a bit via an announcement in the developer wiki which said they were working on a way to re-engage those users which hadn’t bookmarked an application. Since then there has been few updates aside from pushing back the timeline within the Developer Roadmap by a few weeks. So what lies ahead for developers?

Facebook has already begun testing out various iterations of their new homepage design and developers have been able to test out the new counter APIs for a few weeks now. How those counters perform is not yet known, but some developers we’ve spoken to are relatively confident that Facebook will provide sufficient communication channels for engaging users. Despite the occasional protest from developers, the impending Platform changes have been proceeding, albeit a bit delayed.

Just last Friday Facebook announced one breaking change for applications:

Historically, when a user who hadn’t authorized an application first visited that application’s canvas page, the user would typically get redirected to tos.php. After the user authorized the application, Facebook would redirect the user back to the application’s canvas callback URL and include a GET parameter named “auth_token.” Over time various fb_sig parameters were also POSTed to the canvas callback URL, so eventually auth_token became superfluous. After the January 12, 2010, weekly push, we will stop passing auth_token to the canvas callback URL when redirecting a user after authorization.

It’s not a massive adjustment but if you aren’t paying attention to Facebook’s updates, your applications may break. The minor adjustments pushed out so far (bookmark button, old stream API deprecation, revised feed forms, etc) have gone off without a hitch but the biggest changes have yet to come: the homepage redesign, access to user emails, and the deprecation of notifications. All of these changes are still scheduled for the next few weeks, although Facebook has yet to clarify how non-bookmarked applications will re-engage users.

That’s why some application developers had been posting bookmark buttons within their notifications, although Facebook later disabled this feature. With impending changes that have yet to be clarified by Facebook, many developers are doing whatever they can to ensure they can re-engage users under the new system as it has been outlined so far. We’ll have to wait and see what new interaction points Facebook provides developers with, but expect big changes to the Platform in the next few weeks.