For what its worth I just did a recent migration from Sybase to Postgres 9.0 for x64.
I just used some simple tools:
1. Used the Sybase Central dbunload tool to dump the entire database (mind you this is a really simple db not fancy stuff like triggers etc and no indices - had to add that after manually.)
2. Edited the "reload.sql" that the dbunload produces to conform to the Postgres dialect for the "COPY FROM..." syntax
3. The dbunload produces an "\unload" folder containing all the tables in xxx.dat format (the xxx is a number). However I had to edit each table to remove the first three characters/bytes because they screw up the PK ID for some reason. (Most editors will hide these 3 bytes it seems so look for one that can display it - I used the editor that comes with MyEclipse but there should be others that can show hex bytes)
4. run the modified reload.sql via the Postgres Psql (or like me create a batch file/script to do all the command line stuff finally invoking the reload.sql and capturing the output into a text file for later analysis.)
Please add more helpful hints since this might be an interesting tips topic.