1. We plan on offering Sponty in many different languages. 2. It also works great on the iPhone (and similar phones) and it doesn't require a time commitment like social networks do. We really want you to be in and out in three seconds. 3. Soon we'll add more authentication options. 4. Sure, SMS works great for one-to-one. However, it really does'nt scale if you'd SMS all your friends to see if any of them are up for grabbing a bite.
Not trying to sound mean but I often read arguments like that for the next big social web thingy and I find them very contrived. Coordinating group events is certainly an interesting application but I think you should find a better use-case than "grabbing a bite".
Remember people are just animals and strongly conditioned on taking the path of least resistance - especially when hungry...
And I really like the calendar that shows all my friends and what they are doing today. That would be really nice in Facebook and at this point I don't know if that's enough to not just sign up for another service, but also check it and get friends using it.
I can see someone who just wants to login, see what's going on and if there's something s/he can join and then log off and go. And I don't think being part of FB hinders that. It probably helps.
- I'm not in USA.
- My friends are really reluctant to start using new services. It took ages for them to start using Facebook.
- My friends probably do not have Google accounts. In fact they would probably be more likely to use this if this was a Facebook app.
- As you say everyone needs to eat, so it is safe to assume that each of my friends will have dinner anyway. So if I want to have dinner with a particular friend, can't I just SMS them? I think they would find this more natural than me trying to talk them into signing up for something.