The problem is that Google has tried this before and failed. Buzz was supposed to capture the same audience as Twitter, but it has failed to do so yet. I know plenty of people who use Buzz, but none who use it like Twitter. Mostly, I see people who don't use Google Reader picking up shares from people who do. Other than that, though, I don't know many people who use Buzz, and I have a ton of people on my Gmail contacts list.

Yes, adding a check-in service to Latitude could capture some of foursquare's market, especially those who are already using Latitude. Yet I'm sure that most people who currently use Latitude are at least aware of foursquare. If they want such a service, they're probably already using it. If they don't want the service, I don't think an offer from Google would get them to change their minds.

Buzz never really compared to Twitter because Twitter already had a rabid user base. I think foursquare, while not nearly matching the passion of Twitter users, has a similar overview. The people who use foursquare love it. Why would they switch to Latitude? It would require a large group of people - an entire social circle - making the move. I just don't see that happening.

Latitude is still an excellent product, and there's probably no harm in adding a check-in service. I just expect it to be more like Buzz and less like Twitter.