Late tomorrow, Facebook’s going to make an announcement of some sort, and if rumors are correct, an important product will launch.  Facebook is supposed to unveil a geolocation service at its headquarters.

This isn’t a sure thing; official messages on the subject have been very vague, just providing a time (4:30 PM PDT) and an address (1601 California Avenue in Palo Alto), and saying that unspecified "Facebook executives" will be on hand.

Many people are willing to bet that Facebook is connecting its social network to the physical world, however.  Kara Swisher wrote last night, "[A] multitude of sources indicate that Facebook will finally be rolling out its own geo-location offering and the date now looks set for the day after tomorrow."

There will be lots of ramifications if that’s the case.  Privacy is one thing Facebook will have to address straightaway, since few people will appreciate the idea of having their location shared with everyone, all the time.

Then it’s necessary to consider the effect this might have on the smartphone market.  After all, if Facebook manages to make geotagging mainstream, a whole lots of its 500 million users may feel enough pressure to finally pick up an iPhone or Android device.

Finally, if Facebook manages to make geotagging mainstream, that’ll mean it’s succeeded where companies like Foursquare and Gowalla failed.  And that could spell doom for those organizations, even though they’ve been tech industry darlings of sorts up until now.