To me it's pretty close to fishing. For the non-technical user it looks like this:
Quickly grow your professional network
[Textbox with my email address pre-filled]
A Continue button
Looks clever, so you click on it and there's some words, but the Next button is all that matters for these things isn't it?
And woops! LinkedIn has just kindly spammed your entire address book with 'invitations'.
In the past two weeks three friends/acquaintances have been caught out.
For me, there is no way that I would ever ever consider entrusting my email account to a third party. But if you consider that quite a lot of people could have the same password for LinkedIn and their email, they could quite conceivably think that they are logging in to LinkedIn. I mean why would LinkedIn want you to login to your email?!
So, the court case will probably go nowhere, but for me, this is about the same level of suckitude as the Ask toolbar in Java...