The current version is not 3.6v527 as listed here but 3.0 (Build 527)

• New Pulse tab replaces defunct Permissions tab in Address Book Plaxo dock
• Fixed shifting All-Day events for locales in +GMT timezones
• Fixed potential issue of selecting a default Contact sync folder
• Fixed sync problems with mobile phone numbers which often lead to duplicates on a contact's record
• Restored Plaxo membership badge in Address Book (for Leopard)
• Localized tabs in Address Book Plaxo dock for all supported languages
• Fixed sync problem when moving an event in iCal from one calendar to another then quickly deleting the former parent calendar
• More low level optimizations and fixes throughout Plaxo for Mac