As far as PSP's are concerned, Go's are the ultimate fail. They won't be hacked (if any, at all) for a long time because developers will probably be more interested in the new platforms to be revealed at the E3 convention in June.
Not really any hacks, no. People are working on v6.20 exploits, but since the vast majority of existing homebrew won't work with FW v6.xx due to all the stuff Sony removed, I don't really think anyone sees much point in that.
I've bought a ton of stuff from the PSN for my Go and don't regret any of it. I just use my hacked PSP to try before I buy.