PDF Import does not show in Extension Manager. It was installed on LO4 and Debian Testing (Wheezy) via “aptitude install libreoffice-pdfimport”.
It is interesting to see that the very first item under features (/www.libreoffice.org/features/extensions/) is PDF Import, but it not found anywhere at the Extension Center (extensions.libreoffice.org/extension-center). This needs to be corrected, too.
Also, it still very problematic with many PDF files.
Last, but not least, the TAGS box below needs to be adjusted to allow more than 20 characters per tag. For example, I just tried to enter “libreoffice-pdfimport”, but it did not allow.