Since Red Power is full of redstone logic devices and MC 1.5 is a huge update to redstone, AND there was no way for the mod developers to determine the solid build of 1.5 due to extreme changes in every snapshot; I'd guess it'll be a while most likely.
That's actually a misconception.
Yes, redstone was bugfixed a whole lot. But, see: Redpower doesn't actually depend on redstone. It uses red allow wire and its derivates, which is Eloraam's own code. If anything, this makes Redpower remarkably
independent from the changes. Potentially there are some changes in the way the redstone signal is passed from one block/carrier to another, or somesuch, but that's hardly anything that requires serious work. It's probably something she can go through in an hour or two, and whether she actually needs to fix something isn't even guaranteed.
Now, the Redstone Update brought quite a few changes
feature-wise. For starters, the analog nature of the redstone signal (where signal strength matters). This is what Eloraam can (but does not have to) spend a lot of time on. Previously red alloy wire was just redstone that could go up walls and lasted 256 instead of 16 blocks; pure convenience features. But now with signal strength, the vastly extended range becomes a game mechanic concern. If Eloraam wanted red alloy wire to implement signal strength (which it currently does not do), then she'll have to rethink the whole concept of it and everything that depends on it.
But then again, this is a
can do, not a
must do like the huge 1.3 rewrite was.