There are no concrete plans or deadlines for the disc version yet, though it's something that Alec (and I believe Derek) still wants to do. The trouble is working out the cost/logistics behind it. I'm sure Alec will make a big post if/when plans are made.
As for Plimus; while I'll agree that they are a bit poopy, 10% is not much of a cut to give for their services, and I think it's less than what Steam takes (but don't quote me on that)... recently, an iphone game publisher Alec was looking at for other projects was asking for 70%, if memory serves me right.
In any case, what Plimus offers is, as Chibi said, purchase forms and credit cards forms and all the security that has to come with that (it costs companies money to take credit cards as payment), a server for the game downloads, and some support for the purchases. This saves Alec and Derek a load of time and money, so 10% is not an unreasonable amount to give in return. Considering that they're both really busy working on other projects, it would be impossible for them to singlehandedly take on the business end of things as well.