I've started giving my 7 yrs old a lot more freedom than she has before. She's mature and very capable and understands about boundaries and speaking with strangers. For example, she does play outside completely alone or with friends, she is also able to cross our road to get into our van (we park it across the road during the day, residential area) on her own, and while we're out at the store she is able to leave me to go to another section (relatively close by) to look at what she would like to, as long as she lets me know. My rule is that it's ok to talk to strangers but it is absolutely not ok to go anywhere with a stranger. There are millions more nice people in this world than not nice, so if someone says "hello, how are you" I think it's ok for her to answer politely.
Has anyone seen that scary but awesome video of the 7 yrs old girl in walmart where a man attempted to abduct her? She fought and FOUGHT and he very quickly gave up and ran off (to be later caught by police). I showed this to my daughter and told her to do exactly this. FIGHT and SCREAM if anyone ever tries to take you anywhere.
As for my daycare kids (ages 19 months, 21 months, 3, 3 and 5), I do allow them to go outside as they are ready, and if it gets close to lunch time I do leave them outside while I begin to prepare (fenced in play yard, and I leave the door open with screen closed so I can hear them) their meals.
oooo! I just thought of another "independence building" thing I do. When we walk to the park and need to cross the street I let the KIDS tell me when it's safe to go. This way when the time comes to do it on their own, they'll have experience under their belts!