Last night, at the San Francisco New Tech event, more than 50 people checked-in using Foursquare.  Only a handful of people did it via Gowalla.  Nobody used Yelp.  That pretty much does it for me: I am focusing on Foursquare from now on.

This month's San Francisco New Tech event took place at Mighty.  As I've been doing, I checked in with Foursquare, Gowalla and Yelp.  I noticed then that that there were a few people already checked-in with Foursquare and I thought that was pretty cool since I am usually the only person checked-in at the places I frequent.

During the event, I looked at the lists a couple of times to see if anybody else had checked in and I noticed that the list of people using Foursquare was getting longer faster than those using Gowalla.  (BTW, I could not figure a way to find the same information using the Yelp client.)

This morning, I got an email from Foursquare alerting me that I had "unlocked the Swarm badge!"  It turned out that more than 50 people checked-in at Mighty last night.  They called it "a foursquare flashmob!"

Now, I realize that this was not a scientific sample, biased heavily towards the tech crowd.  But then again, that is the very crowd I want to hang out with!

I think this makes it pretty clear that, at least for me Foursquare is it.  As I reported earlier, it is not my ideal location-based client.  For example, Gowalla has better usability and both Yelp and Gowalla do a better job of identifying where I am at: they always put my current location at the top of the list, whereas Foursquare is more sloppy about that.  In spite of that, one important thing about these services is finding other people in real life that I may want to meet and "everybody" is in Foursquare, then that's where I'll want to be.

I will keep the others around for a while and I'll keep checking the activity on them.  But I suspect that over time I'll use them less and less and, eventually, I'll remove them from my iPhone.  Well, I'll still keep Yelp, but for reviews, etc., not for checking in.  Gowalla may be the biggest loser in all this.

In case you're wondering: Sekai Camera is still very immature and not really useful.  In particular, it sucks up power like there's no tomorrow; I can literally watch the battery go down as I use it.  I thought of getting one of the cool battery packs/sleeves, but that would add unwanted bulk and weight to the iPhone (and they're pretty expensive still).  Not worth it at this time, in my opinion.

What about you?  Are you using any of these services?  Which one?  Please, share your story in the comments below (or using Google Sidewiki).

UPDATE: Foursquare and Gowalla released new version of their iPhone clients to coincide with the start of SXSW.  They are both prettier but buggier, particularly Foursquare's.  In fact, Foursquare released an update to the update three days later :)