Since the E61 is the latest mobile phone/PDA device from Nokia, and it's still a new thing, there is no iSync support yet (although Bluetooth pairing and browsing the device works just fine). So here is what you have to do to enable basic syncing of contacts and calendars/ with iSync Version 2.2.
First open /Applications: iSync.app: (Control-click and choose Show Package Contents): Contents: PlugIns: ApplePhoneConduit.syncdevice: Contents: PlugIns: PhoneModelsSync.phoneplugin: Contents: Resources: MetaClasses.plist file in TextEdit, and add the following XML lines:
<key>com.nokia.E61</key>
<dict>
<key>Identification</key>
<dict>
<key>com.apple.cgmi+cgmm</key>
<string>Nokia+Nokia E61</string>
<key>com.apple.gmi+gmm</key>
<string>Nokia+Nokia E61</string>
</dict>
<key>InheritsFrom</key>
<array>
<string>family.com.nokia.serie60v2.3</string>
</array>
<key>Services</key>
<array>
<dict>
<key>ServiceName</key>
<string>com.apple.model</string>
<key>ServiceProperties</key>
<dict>
<key>ModelIcon</key>
<string>NOKNGAGE.tiff</string>
<key>ModelName</key>
<string>E61</string>
</dict>
</dict>
</array>
</dict>
Please note the family.com.nokia.serie60v2.3 line in the above code. In that line, the serie60v23 tag is for Symbian 8.1. The E61 device has Symbian 9.1, but that 2.3 is the latest that iSync understands. So, just leave it like that.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060511162644120