I have the same issue. Website gives me a warning, but;
1- I'm using the Mac SlingPlayer software so that doesn't seem to do 'auto updates'
2- When I put Safari in 32-bit mode (as required) and go to watch.slingbox.com it doesn't indicate any update (from 1.3.70) necessary.
Is 2.0.50 US-only firmware? (I'm in the UK).
Thanks in advance.