Here are two anniversarial tweets that appeared Friday evening. The first is from the WhiteHouse.gov Technology account, celebrating the anniversary of the release of the source code for We the People:
— WH.gov Technology (@WHWeb) August 23, 2013
BTW, little secret: TODAY is the 6th #hashtagiversary. I totally punk'd CNBC. DON'T TELL ANYONE!!!!!!!
— Chris Messina™ (@chrismessina) August 24, 2013
(Messina didn't actually coin hashtag on that fateful day in 2007 — that was done a few days later by Stowe Boyd, another early Twitter adopter. See the Spring 2013 installment of "Among the New Words" in American Speech [pdf], which I co-wrote with Charles Carson, as well as Boyd's own recent post on the subject.)
Gordon Hemsley, who spotted the #OpenSource-iversary tweet, wondered if usage of -iversary has been increasing. I think it has, demonstrating that -(i)versary is available for productive neologizing, now that it has achieved the status of what Arnold Zwicky has dubbed a "libfix" (a "liberated" word part that yields new word-forming elements).
X-iversaries have been crossing my radar for a while now. In a July 2010 "On Language" reader response, I talked about how the use of anniversary has been expanded to commemorate non-annual events, as in "one-month anniversary." Alternative terms include mensiversary (in sporadic use since the 19th century) and monthiversary. The former follows classical word formation, but the latter treats -iversary as a blend component (the first stage on the road to becoming a libfix). Another example came up in a Nov. 2010 "On Language" column: blogiversary, one of many blog-blends (a second-order blend, since blog itself blends Web + log).
Since the -i- in -iversary represents an unaccented schwa, it can easily be dropped for purposes of euphony (cf. such libfixes as -[o]nomics, -[a]thon, and -[e]teria). Back in 2008, Grant Barrett spotted liver-versary, used by a recipient of a liver transplant to commemorate her surgery. And in Nov. 2010, Erin McKean announced Wordnik's API-versary (as well as its data-versary). Arnold Zwicky also noted legalversary last year.
One indication of the libfix's productivity is how often it gets applied by contributors to Urban Dictionary. Using wildcard searching on the handy Onelook dictionary aggregator, one can search on all forms of *versary on UD. As you might expect, a large number of entries are sexual in nature, so we find bangaversary, bjversary, boinkiversary, bone(i)versary, cockiversary, fuck(i)versary, sex(i)versary, shagerversary, vaginaversary, and virginiversary, among others. (Cherryversary, noted in another Zwicky post, has inexplicably not received the Urban Dictionary treatment.)
And the X-iversaries just keep on coming. Twitter reveals an endless stream of ad-hoc commemorations: twitter-friend-iversary, vegan-versary, storm-iversary, book-iversary, Foursquare-versary, Etsy-versary, and on and on. If I could find the first time someone thought to treat -(i)versary as a libfix, we could celebrate the versaryversary.