If you've got an HTC EVO 3D, then you're officially in line to receive the Ice Cream Sandwich OS update whenever HTC finishes it up. But if you'd like a taste of ICS now, with everything working, there's a full ICS theme called SupraMOD that can be flashed onto your rooted phone.
It doesn't work with AOSP, MIUI, or Android 2.3.4 yet, but the developer has plans to work on support for the latter over the holidays.
As with the themes for the EVO 4G we've mentioned in the past, this is the equivalent of putting a Trans-AM body kit on a 1987 Nissan Sentra. You'll have the looks and functionality, but you're not suddenly going to go 0-120 in seven seconds. However, the windshield wipers work and you don't flip the car randomly when changing the radio channel, like you do with ICS ports at the moment.
With porting progress going at its own pace, this theme might be the closest you'll get to seeing bug-free ICS on your EVO 3D until early 2012.
As with any flashing, make sure you have a Nandroid backup made in case something goes horribly, horribly wrong.