As of this moment, the whole deal with ICP and HDMI is non-existent; you can still play full Blu-Ray movies in full resolution (yes, component does 1080P) with component cables. When ICP becomes the standard (and who knows how long before that happens) then you will see movies scaled down using anything other than HDMI.
The 60GB is worth the extra $100; Wifi is an option that you cannot add later on and it's something that everyone will no doubt have a use for. Sure you can sell your 20GB later on and upgrade to a 60GB version, but seems awfully pointless to me; especially when you consider that the launch lineup isn't worth rushing to get the 20GB for and the eventual loss you'll be eating when you resell a unit that no one is going to want later down the road.
"Nagi, how do you feel about being 'normal'? Normal means that if you leave something alone, it just remains that way forever. So if you can't stand that, then you have to be "not normal" in some area... - Seiichi Kirima's dying words