Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
When RedHat switched to a modified business model as part of their rebranding for RedHat Enterprise Linux (RHEL) in 2002, I parted ways with using their distribution at home. Shortly afterwards, CentOS Linux became available as another RHEL-derived option. The glory days for CentOS were the spring of 2007. RHEL5 shipped on March 14th that year, and CentOS followed with their CentOS5 release less than a month later. With some older competition like White Box failing to ever deliver a RHEL5 based release, CentOS has been the distribution to beat ever since, if you want a free-as-in-beer Linux that's as similar as possible to RedHat's Enterprise product. That's made it easy for me set up CentOS systems whenever necessary at home, while also having RedHat's commercial product available to recommend too.
The ugly memories of watching White Box shrivel up and die after failing to deliver a RHEL5 distribution have been coming back lately. RHEL6 was released in November of 2010, tomorrow it will be exactly six months old. There is no sign of a CentOS6 yet.