At the time of writing (6th Nov. 2014), the current version of V-Ray for SketchUp does not officially support SketchUp 2015. However, Chaos are in the final testing phases of an update which will include support for the new version including a 64bit version of V-Ray for SketchUp to match the new 64bit version of SketchUp. Although we can not say for sure when the update will be available, we can assure you that Chaos are doing everything they can to both make it available as fast as possible and make sure it’s working.
The free update will be available for current V-Ray 2.0 for SketchUp users (Educational customers, will need to email firstname.lastname@example.org for update information).
If you are unable to work without V-Ray we would recommend delaying your upgrade to the new 2015 release until the update has been made available.
(Chaos are unable to guarantee that scenes that have been worked on in SketchUp 2015 will still work if opened with V-Ray and SketchUp 2014.)
We will continue to work with Chaos and keep all SketchUp and V-Ray users up to date with any new information we receive on the release.