Some additional Comments...
1 - You can increase the 4 hour Application Polling schedule via an update to the Registry. This is very convenient with you don't want to wait up to four hours.
2 - An Application control policy is not required, but recomended if you want to make the application required or if you don't want constant security prompts to the user (when invoking the phone, etc.)
3 - If you receive a never version of an application already deployed to the device, the new version should be listed in the software configuration. It becomes listed after you re-index the applications on your BES (the new *.alx file should have the new version). This is how the BES knows to push out an update (it compares the version on the device with the version in the software configuration). IF you have changed or added an application control Policy, the upgrade may not push out. This is a bug in the BES software, an SDR an workaround are available (involves editing the SQL tables).
4 - If you're deploying an application to an 8700 device (4.1 O/S), you will need to install the 8700 O/S on the BES. This will be the case until you upgrade your BES to 4.1
That's all, hope this information helps. Some of it has taken many, many hours to resolve, hopefully it will save someone else some time.