GreyBox - I've downloaded the new version but I have some recollection that I had to fix something for localization so I'm not making a change on that right now. I'm not aware of any problems with the version we are using.
Lucene.NET has not made an official release since March 2007, I am already using a build I made myself from their svn repository. It might not be the newest but it works and I feel no need to stay up to date with their svn development unless trying to solve a bug.
FastCSV reader is something I used once for a customer project, I will update the library when I get a chance but as far as I know it is not used in mojoPortal currently.
Json.NET was something I was experimenting with at one point. As far as I know it is not used anywhere in mojoPortal. If I experiment with it again I'll try the new version.
DotNetOpenAuth is a particularly problematic one historically. I will upgrade when I have time but it will require good testing. It is not currently broken so it is not a high priority. I think most people are using the RPX service for open id these days.
DDay.iCal is not currently used but if/when I start using it I will get the latest version.
DayPilot is only used in my paid product Event Calendar Pro and I recall having to customize it so I'm not updating that one right now.
Timeline.NET - I am using a custom build where I fixed a number of bugs and localization issues. I submitted my fixes but they never used them and have not put out a newer release than what I have anyway. The project is not being maintained as far as I see.
Oomph has not put out a new release since Aug 2009 and the official release has some issues. I'm already using a newer version from their repository from about Sept 25 2009