Finally moved my addresses from my Palm to my Droid today. Some fits and starts, but ultimately got there. Basically I exported the addresses from Palm Desktop to a CSV (http://kb.palm.com/wps/portal/kb/common/article/36288_en.html), then imported the CSV into GMail Contacts (http://mail.google.com/support/bin/answer.py?answer=14024).
The export was easy at first glance. Enter the Address section of Palm Desktop (old version used with Centro, so non-WebOS). Select all contacts in the address list then select Export... from the File menu. You may be prompted to show hidden data which likely, you'll want to do if you're migrating fully from one platform to the other.
With the export was complete, I opened up the CSV in OpenOffice Calc. Of course MS Excel, Google Docs or even Lotus 1-2-3 will do. I found that the data came over without column headers. It may be that there was a selection to include the headers in the export that I missed. In any case, I spent about 15 minutes labeling the columns and doing some necessary cleanup of the data export (moving misaligned/misassigned data into appropriate column, deleting empty columns, etc.).
Saving the cleaned up spreadsheet as separate file, I went back into GMail and followed the contacts import instructions (More Actions - Import Addresses, choose local file, click OK, click Import). Worked like a breeze. I even got a message that duplicate addresses were merged automatically. Woohoo!
Reviewing the uploads, it looks like any fields that weren't recognized or couldn't be mapped directly to an existing contact field were added to the notes field and labeled with the header from the CSV. This happened with most of my addresses. In the CSV street address, city, state, zip, etc were each in their own fields. Likewise, Palm Desktop allowed for multiple addresses (work, home). In the CSV cleanup I'd created separate Home labeled fields and Work labeled fields. In the end it looks like the Home City and Home State, where present, were loaded successfully to the contact's address field. The street address and work address info where present, was dumped to the Notes. Likewise for birthdays (which I'd labeled "Date of Birth) and custom fields.