Hey, MySQL is still missing the 'distance' function (distance between two points) so I wrote a little one for my convenience, hope it helps others, here it is:
DROP FUNCTION IF EXISTS `test`.`distance` $$
CREATE FUNCTION `distance`(a POINT, b POINT) RETURNS double
COMMENT 'distance function'
RETURN round(glength(linestringfromwkb(linestring(asbinary(a), asbinary(b)))));
If you think that this kind of utility functions should ship with MySQL add your voice to this feature request