The Linux Professional Institute is a non-profit organization that promotes the use of Linux and open-source software. They have developed a 3-level vendor neutral certification track for Linux administrators. As of 06/2010 LPI has awarded over 85,000 certifications. Their partnership with CompTIA is likely to further increase their numbers.
LPI seems to be gaining steam in recent years and appears to be a very viable certification that is rapidly gaining respect. There are a reasonable amount of 3rd party preparation materials available unlike some of the other Linux certifications (SAIR being a good example of this).
The table below outlines the various LPIC certifications:
||The LPIC1 certification is for junior level Linux systems administrators and consists of 2 exams. You can take CompTIA's Linux+ and earn both certifications.
||The LPIC-2 certification is for intermediate level Linux systems administrators and consists of 2 exams. LPIC-1 is required as a prerequisite.
||The LPIC-3 certification is for senior level Linux systems administrators and consists of a choice of 2 exams from those offered. LPIC-2 is required as a prerequisite.
Useful Official Resources: