A user has pointed out that this drink is pretty similar to the Victorian Gentleman's Gimlet, which was created and posted long before this was. Unless people object, I'm going to merge this in a couple of days - each has about 20 users. Thanks, Zachary
"Eastside" (one word) seems to be a more popular name and may predate that German gimlet. The "Eastside Cocktail" appears in Imbibe dated 2009 and "Eastside Gimlet" in Diffords, where it is claimed this was a 2004 long drink by George Delgado (Libation, NYC) before the up version was popularized by Christy Pope at Milk&Honey. Punch and others haveb obvious riffs on this (with gin and cucumber) called things like "There is no Eastside".