I started toying with GAL Sync in FIM 2010 RTM and here are some mistakes I made. Perhaps somebody else might be making the same mistakes.

At first all users/contacts were appearing in the MV, but no exports were being proposed… This was due to the fact that I hadn’t enabled provisioning in the Sync Manager options:

The second problem I was seeing was a lot of users being added twice into the MV and eventually into my portal. This was because the already present AD MA didn’t synchronized any attributes which the GAL MA uses to join upon. Therefore I extended the GAL MA to also use the employeeID as a possible join attribute:

After cleaning the CS of the GAL MA and doing an import again, things started looking better!