I'm getting mixed results with an update site I'm setting up:
I got some hints about p2 metadata missing - does anyone know what's missing?
Update: Both artifacts.xml and content.xml have references to the 3.0.2 version.
I saw a blog about this at http://www.jroller.com/andyl/entry/p2\_is\_my\_best\_friend
It seems that it has to do with how the p2 repository is generated for 3.5.
There are some comments on the above blog on how to fix/workaround the issue. I see your on the developer list for mylyn-mantis, so one of the workarounds might help you.