The Beta versions of the Mobipocket Reader can be easily differenciated by their build number.
This build number is available in the About Box of the Mobipocket Reader on the BlackBerry.

To display it, launch the Mobipocket Reader, select the About menu.
A message box will display some informations about the Mobipocket Reader.

These informations will for exemple contain the folowing line :

This number allows the Beta Testers to know if the bug they might find has been fixed since they have downloaded the Mobipocket Reader Beta version, and if so they can download the new version.

January 19, 2009: Build 80 beta

• New feature:
  • Support of BlackBerry Storm - 9500 phone series.
  • Support of BlackBerry Bold - 9000 phone series.

• Bug fix:
  • Fix of a crash during over the air eBook download.
  • Fix of some sub-menus which were not displayed on some BlackBerry devices (e.g. annotations sub-menu).

September 09, 2008: Build 79

• Change Log :
  • Password encrypted eBooks are now fully supported.
  • Fix of error message displayed when some eBooks were opened.