Epson not only offers MHL on one of its two HDMI inputs, but goes a step further and offers Miracast built in to its wireless capabilities. Let's talk Miracast first. This allows you to stream content (movies, games, whatever) so that you are showing exactly what's on the source's display (could be a laptop, tablet...)
Miracast is first, a certification process for peer to peer wireless. If a projector (as a display device) has Miracast, it can display what the source screen displays. It does this wirelessly from devices that also support Miracast. Note that Miracast supports only certain protocols, so it doesn't work with all or most peer-to-peer solutions out there. But, in most cases, two Miracast devices should work together.
There are resolution limits. Officially Miracast will stream up to 1080p (1920x1080), just a little less than the maximum native resolution of this projector at 1920x1200. Miracast also supports audio up to 5.1.
Think of it this way. We're used to communicating wirelessly in many cases over a local WiFi network. MHL is an example of that. Take an MHL source - such as some of the Android tablets, and they can, using your home WiFi, talk to a display that supports MHL, such as this Epson PC1985W projector.
If you have no WiFi network at your location, you have no working solution with MHL. On the other hand...
With Miracast, it's just the two devices - using WiFi technology - notably what is called WiFi Direct connection. (The folks behind all of this is the Wifi Alliance.) The two devices need no network, just two "peers" - your two devices talking directly to each other.
This makes for a simple way to wirelessly transmit, for example, what's on your laptop or tablet or phone (if Miracast compatible), to your projector, in this case, the PC1985.
It gives you another alternative method of communicating, without running heavy HDMI cabling, or lighter USB cabling for those devices supporting USB Display. With Miracast, and the 1985 projector, and the right devices, no cables! Miracast is found in many Android devices, and support is part of Windows 8.1. That said, on the Apple front, (we're an Apple shop) there's no support, as Miracast is essentially a competitor to their own peer to peer network known to us Apple users as Apple TV. If I want to do the equivalent to Miracast, I would plug my Apple TV into one of the 1985's HDMI ports, and accomplish the same thing - displaying what's on my MacBook Pro, iPad, or iPhone.