Khaled has stated that there is a newer version being worked on, and I would be very surprised if it wasn't set to work with Windows 7 and the various differences that Windows 7 requires, as well as maintaining compatibility with earlier versions of mIRC and Windows.
As to when the next version will be out, which I know you didn't ask, but is probably something you're wondering about, like the rest of us, all you can do is wait.