Funambol has an open source approach to Mobile Email and Mobile Sync. Some say that Funambol is out to take out RIM. They have a model similar to what I saw last with SugarCRM - free for Enterprise IT users or personal sync and you can buy the enterprise edition. I think that is a good model and the space needs a competitor as well. The software appears to be licensed under the AGPL, again I have seen that after a while. For those not familiar with AGPL (Affero GPL), it is a stricter form of traditional GPL license in that you cannot even host it w/o disclosing source code.