The best Slingbox available only supports input resolution up to 1080i and doesn't have an HDMI input.
So the next two questions are:
Do you need 1080P input into the slingbox to stream 3D content?
Can you view 3D content via component (analog) input?
And even if the answer is yes to both of those, minimum upload speed at the Slingbox needs to be 3mb for you to test it. From the slingbox website:
" Tune in to 1080i HD - Viewers can watch their favorite shows in stunning HD over the Internet on their PC or Mac, desktop or laptop, around the home or around the world.
*Requires a high-speed broadband connection with 3 Mbps or greater bandwidth"
This why I decided to save money and go with the Slingbox Solo. I figure by the time an ISP offers those kind of upload speeds in my area, there should be a new Sligbox model that supports HDMI. Fingers crossed waiting on Verizon Fios