Myself, I'm very happy about WikiLeaks' work. Even though my political ideas are probably far in many repects from most of its supporters and even Assange's. I think it's important that politicians be accountable. If they can do whatever they come up with without voter input, democracy and republicanism are over--not to mention if voters don't even know in the first place.
There are two separate parties here that tend to be identified: WikeLeaks itself and the whistle-blowers. The latter have most times committed some fault, if they were government officials they probably broke some oath or otherwise are at fault and liable to be prosecuted. They were likely aware of this and acted under their own responsibility, considering the personal consequences versus the goals they wanted to advance--most likely unselfish.
By the way, let us hope, that government officials are still liable to criticism as well, or even prosecution if and when they're at fault.
On the other hand there seems to be very little ground, legally first of all, to prosecute WikiLeaks itself. It's in a very similar position to traditional media that have disclosed classified leaks in the past. The only difference is the scale, the Internet is more powerful than earlier media against governments.
There's also the point that Assange himself needn't and mustn't be identified with WikiLeaks. There are a lot of reports about him in the press, and they all should probably be taken with a grain of salt, but it seems Assange has a good deal of virtues as well as flaws. And although his personality shouldn't be of our concern, we don't have any strong reason to believe that the charges brought against him in Sweden are fabricated. Be that as it may, I've also heard that he's faced a lot of criticism and dissent from within WikiLeaks. What I'm saying is that even if something happened to Assange (and I don't mean anything conspiranoid), that would not be the end of this. Actually some of the most prominent dissenters are already busy founding a competitor to WikiLeaks,
http://openleaks.net/, but even WikiLeaks may survive (metaphorically) Assange.