Weird... My slingplayer is still working without issues after 2.2. I was having issues getting flash to work until I did a battery pull and since I've had no issues with 2.2 since. Maybe this will work for you...?
*edit: I went into the market and you are correct, it isn't located in there as of now. I have slingplayer on my home screen, maybe this is why I didn't lose it... I have faith it'll get resolved, when I bought my x on launch date it wasn't thee for a day and a half, I'm sure they will resolve quickly!