brynn current reply:
No, for me, snapping group centers can only happen when snapping to nodes is off.  I've also just tested in Inkscape 0.91 64 bit (7z version).  For the 32 bit version, I used exe installer.  Windows 7, 64-bit.

brynn current reply:
Yes.  We've been getting questions in forums about this, since 0.91 came out.  For example, in 0.48.x, a node on a path would snap to another path, with having only Snap to path enabled.  Now, Snap to nodes must be enabled too.  And it's a good idea to have snapping to both cusp and smooth, because in 0.91, Inkscape can't always tell the difference which type of node is which.  I think I made a bug report about that.....can't remember for sure.

brynn current reply:
As I said, the center of groups can only snap (to anything) if snapping to nodes is disabled.

brynn current reply:
I could send you a screenshot, but I'm not sure if it's needed.  With further testing, I was wrong about that.

I can snap a group center to: path, path intersection, bounding box corner, bb side, bb side midpt., guides and grids

I cannot snap a group center to nodes, bounding box center or line midpoint.

And as I said before, group centers won't snap to anything, unless snapping to nodes is disabled.

Details:
When I try to snap to bbcenter, just nothing happens.  When I grab the group with the mouse, the group center becomes a red dot.  But it never recognizes the bb center.

When I try to snap to line midpt, when I grab the group, the red dot does not replace the group center.  It replaces the line midpt closest to where I grabbed with mouse.  So the group center can't snap because there's no red dot there.

If you need anymore details, let me know.  I can send screenshots if you need.  Although I don't have a very good program, and it can't catch the mouse or tooltips.  But Prnt Scrn catches the red dot.