It looks to me like there are write operations for status, activity stream, friend invitations, and direct messaging. I'm not too surprised that LinkedIn does not offer all the contact details.
Phew. This documentation is organized in a somewhat annoying fashion.
Imaging Google not allowing you to see the email address via their ContactsAPI, that wouldn't make sense...
Too little, too late. From my experience, linkedin has lost a bit of steam over the last 6 months or so. I used to check the site regularly, update contacts, join discussions, etc. but have not done so lately.
I was initially excited by the first release of API but was disappointed after digging into it a bit. Having to apply etc. just killed it for me (I eventually got accepted but by that point had no interest). This release is more of the same and is rather limited as spif points out.
However it's not as good as it seems:
1. There is no support for contact details like phone-number, email etc.
2. The API is read-only, and that sort of beats the purpose of this API.
(At least judging from the limited documentation available at the moment.)