Gogle has just announced that starting today, Google Apps for Business, Education and Government customers have "space for twice as many contacts as before in their organization's shared contacts."
"IT administrators told us that they needed more capacity, so we upped the limit from 25,000 to 50,000 entries. Shared contacts are part of the organization's global address list (GAL), and these contacts auto-complete across Google Apps to help employees work faster and more accurately," said Google.
Once you start typing to address an email message, invite colleagues to a calendar event, or share a Google Docs file, you can just click a recipient's name to complete the entry.
Also made optimizations to the Shared Contacts API so administrators can upload contacts much more quickly.