Acorn 4.5.3 is out for direct customers. It's a maintenance release, containing mostly bug fixes. Make sure to grab it though, as I believe I've fixed the #1 and #2 crashers that I'm aware of, which makes me very happy. One of these has been around for a number of years, and it was only recently that someone gave me a reproducible case for it.
I'm still working on the App Store version. I had hoped to have it submitted already, but I've got new signing certificates and something on Apple's side keeps on rejecting my upload. Previous builds of Acorn were done on 10.9, and I'm doing everything on 10.10 now, so I'm guessing that's part of the problem.
It should be out reasonably soon (by App Store standards), maybe a week or so?
Update: I ended up doing the build of Acorn 4.5.3 on 10.9, and iTunes Connect took it just fine. So we're just waiting on Apple to review it for the App Store.