Well, they did as their name suggests :) These little ponies had the same translucency as the Sparkle ponies, but instead of glitter they were sprinkled with hearts and stars, the latter of which glowed in the dark. There are several salient points to be made about these girls. Firstly, despite being labelled 'Glow and Show Ponies' in the USA, the American produced My Little Pony Tales series featured them in an episode called 'Up Up and Away' under the label of 'Glowing Magical Ponies'. Though suddenly featuring wings and horns and all kinds of weird mystical powers, this is in my mind one piece of evidence that perhaps the MLP Tales series was *always* intended for a European/UK audience.
Also, it is important to note the following. Some strange individual, (I do not know who, which is probably a good thing for their sake) began the rumour that the 'blue heart' version of Dazzleglow (left) was the 'UK version' of the pony. Mm. Ok. Well, here's the truth. There is only one form of Dazzleglow in the UK - that's the one above, with pink hearts. Secondly, the blue hearted Dazzleglow appears in the American 'Glow and Show' commerical (yes, I have this on video :-D). Thirdly, the pony only ever appears for sale on ebay from North American sellers - in fact the one pictured is the only Glowing Magic Pony on this page that I had to import from America to have in my collection :P.
 Therefore the conclusion is logically as follows. Europe and the UK had one Dazzleglow - pink hearted, as above. The USA had BOTH blue hearted and pink hearted Dazzleglow.
Perhaps the source of the confusion is the appearance of the blueheart Dazzleglow on the UK insert and card, but this can be explained very easily. Hasbro had a pattern of issuing ponies in the UK a year after their US issue. Therefore, and the Glowing Magic Ponies are not the only set this applies to, American issue ponies were often used to advertise the set in the UK.
The second variation I have found is less straight forward. The Starglow at the top, with the dark pink in her hair I can account for since she came off her card, since she was my sister's childhood pony and she had her from new. She's definitely a UK born pony. The second Starglow (right) is my one, and came from the toy fair at Birmingham NEC. I have no clue however if she originated in the UK, and I've certainly never seen another. Anyone know?