The Cowper's glands sit in the urethra below the prostate and produces a natural lubricant - some men (and pre-pubescent boys) produce a lot and others so little that they would never notice it. Whether the glands are removed depends on how much of the urethra has to be lost - perhaps men with a small prostate are more likely to still have their Cowper's glands post-RP. I am pretty sure John doesn't have one anymore as there is never any sign of stickiness but he had a major restructure of the bottom of the bladder, urethra etc so not really surprised.
However, the lubricant doesn't spurt out like an ejaculation - more like it oozes out. The equivalent in a woman are her Bartholin glands which lube the entrance to the vagina.
What is interesting about the Cowper's gland (and Bartholin) is that the liquid it produces contains some PSA, another reason that no-one ever gets a true zero even if their cancer has been eradicated? Might also explain why a woman can have a PSA of up to 0.05 after an orgasm ;-)
I can't remember the name of the guy now but there was a member of YANA who had raised PSA and all biopsies were clear who was eventually diagnosed with cancer in his Cowper's gland (a completely different cancer to PCa). I guess it would show on a scan though.