Yes, the Get + Past Participle is a more informal version of the be-passive. Here are some theoretical differences (taken from CGEL, the Cambridge Grammar of the English Language): It is used with dynamic verbs (e.g. The village got surrounded (dynamic) versus The village was surrounded (static). If the individual has some responsibility for what happens, get tends to be used (compare He was arrested (he was innocent) and He got arrested (he was guilty)). Compare also "He got himself arrested." Get tends to be used when something happens that is unfortunate or beneficial to the subject (compare He got hurt/His watch got broken and He got promoted). We say, "The door was opened by a small child." We would not say, "The door got opened," since this is of no benefit to the door.

I agree with Ben on both counts: 1. The 'get' + pp is more informal than the passive. 2. The 'get' + pp may suggest that the person was more actively involved in the process.