Found this on the Mars Society web site:

Permafrost Springs on Earth and Mars
by Chris McKay
"There are two sets of perennial springs located on Axel Heiberg Island that flow through 600 m of permafrost and these springs are not associated with any volcanic heat sources. Located at nearly 80N these are the most poleward springs known, and to our knowledge the only example of cold springs in thick permafrost.
"Axel Heiberg Island is mostly bare ground, with less than 35% covered by glaciers or ice caps. The average air temperature at the springs sites is approximately -17C. The two springs both discharge a brine with measured discharge temperatures that range from -2 to +6.5 C and remain constant throughout the year despite air temperatures that fall well below -40C. Flow rates are also constant with little variation."
http://chapters.marssociety.org/youth/mc/issue8/permafrost_springs.php3

McKay et. al. also discussed such permafrost springs in some reports given at LPSC conferences:

Possible Analogs for Small Valleys on Mars at the Haughton Impact Crater Site, Devon Island, Canadian High Arctic
http://adsabs.harvard.edu/cgi-bin/bib_query?1999LPI....30.2033L

Snow and Ice Melt Flow Features on Devon Island, Nunavut, Arctic Canada as Possible Analogs for Recent Slope Flow Features on Mars
http://adsabs.harvard.edu/cgi-bin/bib_query?2001LPI....32.1809L

Note also that Don Juan Pond in Antartica stays unfrozen year round due to high salinity:

Making a Splash on Mars
"One thing we have to be careful of is our everyday experience that water always freezes at zero degrees," noted Hoover. "It doesn't. Water containing dissolved salts freezes at a significantly lower temperature. Don Juan Pond in Antarctica is a good example. It's a high salinity pond with liquid water at temperatures as low as -24 °C."
http://science.nasa.gov/headlines/y2000/ast29jun_1m.htm

Tim Meehan's Antarctic Adventure
http://experts.apple.com/connection/meehan/Science/DryValleys/Boondoggle6.html

This page mentions that Kim Stanley Robinson, author of the Mars terraforming novels, was along on this trip.

Nice pictures of Don Juan Pond as well as other Antarctica areas on this page:

SIUC Microbiologists in Antarctica!
http://www.science.siu.edu/microbiology/Antarctica/Antarctic.html

It mentions that the pond stays liquid even down to -50°C due to calcium chloride content.

Bob Clark