Update: The beta phase has ended. Final version of MAMP PRO 4.2 has been released.
We have released a public beta version of MAMP PRO 4.2. In this version we have added support for dropbox (the integration of more services is planned). This new "cloud service" will help you exchange your projects between your various Macs.
Hosts can be saved to and loaded from the cloud. MAMP PRO will save both your document root folder and database data. Your data for each individual host will be saved in a single zip file in your Dropbox. It is not necessary to install Dropbox software to use this feature, you only need a login to your Dropbox account through the MAMP PRO interface cloud settings. Use the Databases tab to confirm which databases are linked to your host.