Last week it was reported that Facebook would unveil its long-anticipated iPad app during the iPhone event of all places. Of course, the announcements won’t stop there, and the social network will supposedly also show off an updated iPhone app and its HTML 5 Web-based app marketplace in the near future (whether or not these releases take place at the iPhone event remains to be seen).

By all appearances, it seems that things have become rather chummy between Apple and Facebook. This hasn’t always been the case: There have been tensions between the two companies dating back to fallout over Ping, when Facebook pulled integration from the service and Steve Jobs called the social network’s terms of use “onerous.” Facebook’s business relationship with Microsoft and Windows Phone 7 probably hasn’t helped matters either.

And when Apple announced that iOS 5 would feature a deep integration with Twitter, we all wondered why not Facebook? New rumors say that not only will Facebook premiere its own applications tomorrow, but iOS 5-Facebook integration might be on the schedule as well. MacRumors got its hands on a mockup (with more than a few errors pointing out this is not an authentic screenshot) that suggests this is a definite possibility.

Apparently this was all complicated by Facebook’s TouchPad app. When Jobs found out Facebook was building a webOS-based app before releasing its long-awaited iPad app, it was very nearly the last straw. But Facebook then restricted HP’s access to its APIs to appease Apple. And the TouchPad wasn’t long for this world at that point anyway.

But the most critical relationship-mending tactic is reportedly the two companies’ common enemy: Google. Both want to assert themselves over Google for different reasons, and what better way than to unite forces? Facebook recently revealed the importance of mobile to its new platform, and basically set the stage to reveal some sort of integration that will make its Open Graph even more marketable. Think about some of the apps Mark Zuckerberg showed off at f8–all lend themselves to mobile usage. And Facebook needs an established mobile ecosystem to promote this even more–just like Apple needs a social network to compete with its own challengers, who are integrating social networks into their handsets already.

What’s most interesting about these rumored developments is the fact that Facebook’s HTML 5 Web-based app store (or “Project Spartan”) was originally labeled as a way to escape Apple control. We assume that concessions have been made, because while details remain fuzzy, it seems certain that iOS and Facebook have something up their sleeves for tomorrow.