Pasted my response to a recent email discussion:
Sharing my thoughts on FS now - for note, I'm a BlackBerry user who receives email notifications (not Twitter DMs/SMS) and mostly checks in via SMS (occasionally through the mobile web if I need to find a venue name).
In my talks with Matt about this, we've agreed that it's rather annoying (personally) to receive check-ins from people at home, from bed, on highways, on buses or at work because part of checking in to a venue is having it as an open invite for someone to join you (after all, the messaging even says "swing by and say hi!"). Exceptions being coworking or get togethers at your house or work where people are invited to swing by because they're social activities. Checking in to a not-very-open workplace everyday at 9am isn't an invite - it's personal logging (which has a different type of value).
For instance, our friend Lindsay checks in to work at Apple - but it would be really not okay if I randomly showed up to Apple to hang out with her. However, I understand points Ben has made about your friends wanting to know your general vicinity so they can invite you out to other things (like, hey, I see you're at Apple, want to go to lunch at this place 3 blocks away?).
I think what might be needed here is a distinction between check-ins and statuses. I think this might already be similar to shouts - I don't seem to receive notifications of shouts via email, but they're on the mobile web if I wanted to check (ambient). So maybe something like:
Andy S. @ 21st Amendment (notification)
Ariel W. is in transit !on a crappy muni (status)
Leah C. @ Nova (nofitication)
Lynn L. is at home (status)
Lindsay E. is at work !as always (status)
Mike M. @ Six Apart !OpenID meetup (notification)
This may help with maintaining the balance between people who want ambient-only data versus notifications (not just an iPhone vs. BlackBerry thing, as Leah and I argued that FS completely lost value to us unless it pushed notifications). I feel that Dodgeball made one big significant assumption that made it stand out from things like BrightKite, in that it assumed you didn't give a crap about where your friends were in a different city. Maybe you do give a crap about knowing if your friend is at home or work or on a bus, but perhaps no one cares to receive a notification about it everyday?
As for the gaming part of FourSquare, annoying or not (I'm definitely an advocate for adding gaming-like features to things), it's great for the service. I was explaining the gaming part of FS tonight to people who don't use FS at all. I explained that the "game" does not actually take place on FS so much as it serves for brag-rights/ego-satisfaction to tell people in person that you're the mayor of a venue or that you have more points than them on a given day. The thing that I believe FS has done right is that mayorships and points are something that you have a choice to pay attention to, but if you don't care about it, it's very easy to just use the service for the basic functionality.
Ariel