Criminals get Tranquilizer, Anarchs get Botulus, and Shapers appear to get Egret to finish the pattern of 2 cost programs you host on ice. As the earlier reviewer noted, the MU cost can make programs such as Egret tricky to account for, but now we have tools like DZMZ Optimizer or Supercorridor to help with memory.
Rielle "Kit" Peddler: Transhuman gets good use of Egret as it provides her a way to deal with carefully positioned Barriers or Sentries. In combination with other options like Pelangi or Engolo (depending on what format you are playing) Egret lets Kit get through some of the modest glaciers that tend to develop in the mid to late game.
Also interesting with Tāo Salonga: Telepresence Magician, as you can move the ice Egret is hosted on to a more useful position with his ID ability. The Corp can just trash and replace the ice you host this on same as the Tranq or Botulus of course, so try and put this on something the Corp will miss. If they trash it anyway, use Simulchip to have your Egret perch on something else.
On a lore note, the first printing did not include any flavor text, making the connection between the abstract idea of an egret and changing an ice's type a bit confusing. An ancient Egyptian creation myth has a heron (egrets are herons) making a cry at the beginning of the world. In ancient Greece, as the flavor text in the new printing points out, the heron was a messenger of Athena and was interpreted as a sign of her favor. Aztlan ("the place of whiteness/herons/egrets") is the mythical homeland of the Aztecs, although whether it was a paradise or a tyrannical kingdom is unclear. In Asia the heron is a symbol of beauty and in Chinese the word for egret is similar to the word for path or way.
Clearly then the Egret is meant to be a kind of creative blessing, something that perhaps inspires the runner to think outside the box in regards to a certain ice.