MobileMe(TM) is a new Internet service that delivers push email, push contacts and push calendars from the MobileMe service in the "cloud" to native applications on iPhone(TM), iPod(R) touch, Macs and PCs.
It's pretty similar to Microsoft's Mesh software. Essentially, it allows you to do things like make appointments on your phone and have them sync your computer and vice versa, and the updates happen in about 10 seconds. The service will cost you $99 a year for 20GB of space,
MobileMe also provides a suite of elegant, ad-free web applications that deliver a desktop-like experience through any modern browser. MobileMe applications (http://www.me.com) include Mail, Contacts and Calendar, as well as Gallery for viewing and sharing photos and iDisk for storing and exchanging documents online.