It seems there’s some confusion here, despite Cecil’s column.
First, there seem to be TWO “Planck Temperatures”. I’m basing this on an Alta Vista search for the term, which turns up several pages which look vaguely crackpottish to me, Cecil’s column, a couple of “introduction to cosmology” pages which mention the term in passing (all of which use it in more or less the same way, though they don’t all have the same value… see below), and an answer key to a quiz which as far as I can tell (the full text of the QUESTIONS wasn’t provided) is using “Planck temperature” in a way that may be related to the “black body / cavity radiation” answer above. More specifically, they’re calculating the surface temperature of a planet and calling that the “Planck temperature”. Obviously, this is not anywhere near 10[sup]32[/sup] Kelvins.
The actual value of the Planck temperature (in the same sense that Cecil uses it) is not exactly 10[sup]32[/sup] Kelvins. Unfortunately, I can’t tell you what it is, because I can’t find it in any source I trust and the values I find in sources that I don’t trust (the web pages mentioned above) vary considerably, from 1.4 to 3.something times 10[sup]32[/sup].
It’s definitely NOT known to so many significant figures that it makes any difference whatsoever if you express it in Kelvins or degrees Celcius.
The change to “Kelvins” from “degrees Kelvin” was made in 1967. However, while the “Definitions” section of my 60th edition CRC HoCaP correctly explains this, the VERY NEXT ENTRY still uses (degree symbol) K, which terminology was by that time 12 years out of date.