So Jeff Langr has a good starting list on how to spot an Agile team on the right track over here. Clearly a team being "on the right track" needs to go beyond the mechanics and get into the behaviors of Agile. My picks focus less on delivery than Jeff's but here are some things I'd add to the list:

• There are pigs and chickens, but never goats...the attitude is genuinely one of sink/swim as a team.
• The team actively adds/modifies the backlog as issues or opportunities arise throughout a sprint.  I like to see my team actively adding user stories ("Improve exception handling", "Increase query performance", etc.) as sprints move on; that's how I know they've really gelled.
• The team actively mentors one another and calls out estimation problems or boat anchors to burndown progress, dealing with them non-judgementally.  If John Smith said 8 hrs and its been 24, let's help him out.
• Estimations begin to be all inclusive.  An agile team early in the adoption process will estimate time to actually do the work while leaving out any minor discovery or issues redress; things that can add up over time.  A mature agile team rolls this all in to produce a comprehensive estimate that makes burndown and velocity look reasonable. 
• Members "jump into the breach" to help another team member if one's own backlog is finished early...or take more backlog proactively
• Solve problems in the hallway or at the white board without needing to "schedule" an issues meeting...maybe even over coffee in the morning or lunch.

In short, a maturing agile team will stop clinging to process and develop a cohesion that just looks natural.  Nothing get's forced into 15 minutes because 15 minutes is more than enough time.  The backlog is always well groomed because that's the natural thing to do.  Delivery follows on from this..and that's how you get consistent delivery on committments and predictable story completion.