What is an Everstone? It's a stone, which instead of evolving Pokemon (as opposing to Evolutionary Stones), prevents them from evolution.
Those people, that had some of Virtuadopts frozen, lucked out - magically their Virtuadopts received their own Everstones. You can either leave them with stones, or take the stones away.
In the morning of GMT, there will be also small change in the way of how Everstone works - you will no longer be available to freeze eggs, but instead your Virtuadopts will gain levels (just won't be able to evolve).
On a side note, it has been a week since I opened the Virtuadopt to the public. We have got over 500 members, nearly 5 thousands of Virtuadopts were adopted, and you have fed them nearly 200 000 times! That are some pretty impressive results. Thanks for joining, it's thanks to you, that this site lives
The Promotional Shiny Mew retires in 10 hours. Make sure you claim yours, if you hadn't yet.