Sorry, I'm just now getting to this.  I'm not having any problem importing and exporting obj files with Blender 2.62 on Ubuntu, but it's the official download from the Blender site and not from a ppa.  I like to keep several versions on hand for choice and testing.  2.62 actually works great for me, but I haven't taken the time to add some of my key plugins to it, so it's nice to have around my 2.58, too.  That said, I'm getting addicted to the new UV mapping features, like the subsurf aware mapping and straightening.  The new "seams from islands" and UV sculpting feature is tempting me to try remapping Antonia to take V4's textures.   I was kind of annoyed at seeming to lose Join as UVs (copies UV mapping to an identical mesh, which is more useful to me than it should be), but it had just moved.