Rumors have been floating around about Research in Motion’s (RIMM) big entry into the tablet race, the BlackBerry PlayBook, might support Android apps at some point, but a possible slip-up by a RIM rep at Mobile World Congress earlier this month suggests that rumor is confirmed.

There’s been some buzz building around the possibility that the PlayBook will carry some kind of Android support, either when it launches or sometime soon thereafter. The report comes from Yahoo!’s (YHOO) Today in Tech blog, complete with the video of the rep’s (possible) slip.

RIM’s move to support Android would be a pretty significant one. BlackBerry has been in a downward slide in terms of market share as it goes up against Google’s (GOOG) Android and Apple’s (AAPL) iOS operating systems. BlackBerry devices are selling less well, and RIM has less influence over the market with each passing quarter.

PlayBook has been the long-in-development bid to both bring it into the rapidly expanding tablet market, and to re-energize the BlackBerry brand as a leader in mobile business technology — something it was for years before Apple and Google entered the race. RIM acquired The Astonishing Tribe a few months back in hopes of creating a user interface for the tablet that would set it apart from the competition. There are a lot of eggs in this basket.

Adding Android support on top of RIM’s QNX operating system would give PlayBook a head start as it drops onto the track, with a library of about 10,000 apps for the tablet to exploit. PlayBook would probably use Java-based “virtual machine” software, which would allow it to utilize “legacy” BlackBerry apps as well as Android ones, according to The Boy Genius Report.

We should note that RIM HQ hasn’t confirmed or denied any of this Android noise — it’s still just a rumor, and even the flub at Mobile World Congress could have just been a slip of the tongue and nothing more. Mistakes happen.

And while it sounds like a good idea for RIM to push into the Android realm, if PlayBook is doing so, one might consider it an admission of defeat in at least some respect. RIM’s stake in the OS fight has been diminishing — it’s losing that battle — and if it decides to support Android apps, it would appear the company’s strategy at the end of the day is not about backing software, but hardware. This would be similar to Nokia’s stance (NOK), which also considered involving Android in its devices.

Again, not necessarily bad, but if this rumor proves to be true, it seems like it could be heralding a change in the way RIM goes forward with its devices. BlackBerry as a brand is something the company wants to revitalize and strengthen, that much seems obvious; to make that happen, partnerships with the other big players could be on their way in the future.