query the google play store for the version of an app?

Found a suitable API via G+: this is the API: https://androidquery.appspot.com

example call: https://androidquery.appspot.com/api/market?app=org.ligi.fast

and this wrapper/code: https://github.com/androidquery/androidquery

Google Play does not provide any official APIs for retrieving metadata. You could however, check the unofficial API at http://code.google.com/p/android-market-api/.

Specifically, take a look at the Wiki page HowToSearchApps. The response to the query contains version information:

Your query will be something like:

String query = "maps";
AppsRequest appsRequest = AppsRequest.newBuilder()
                                .setQuery(query)
                                .setStartIndex(0).setEntriesCount(10)
                                .setWithExtendedInfo(true)
                                .build();

session.append(appsRequest, new Callback<AppsResponse>() {
         @Override
         public void onResult(ResponseContext context, AppsResponse response) {
                  // Your code here
                  // response.getApp(0).getCreator() ...
                  // see AppsResponse class definition for more infos
         }
});

Your response will be of the format:

{
  "app": [
    {
      "rating": "4.642857142857143",
      "title": "Ruboto IRB",
      "ratingsCount": 14,
      "creator": "Jan Berkel",
      "appType": "APPLICATION",
      "id": "9089465703133677000",
      "packageName": "org.jruby.ruboto.irb",
      "version": "0.1",
      "versionCode": 1,
      "creatorId": "\"Jan Berkel\"",
      "ExtendedInfo": {
        "category": "Tools",
        "permissionId": [
...

Then of course you may use a JSON Parser or do a string search.