I have no inside information, but the iDevGames website has been down for a few weeks now and I don't expect it will come back this time.
Like IMG, the main site has been inactive for years except for the forums. But even that was hobbled-- the moderators closed it to new members because too many spammers were getting through. So the writing has been on the wall for a while.
For those who aren't familiar with it, in its heydey (2002-2006-ish) iDevgames was an influential hub for amateur Mac game developers and its annual "uDevGame" contest launched many memorable free games, gave away prizes worth many thousands of dollars, and even gave some people a pathway into the computer game industry.
I remember some of those old contest entrees fondly, and keep many on my hard drive even though most of them don't run any more. (My own uDG contest entrees are still available on my website mindthecube.com, and I did patch them from PowerPC to Intel, but I have no plans to make them 64-bit.)
Pour one out for another fallen Mac game institution..