I wasn't going to blog about this... but since it made OMG! Ubuntu as a sensational article, I'd be remiss not to mention it.
Yes, it was floated on the ubuntu-devel mailing list to disable the ability to install using Wubi on the Ubuntu desktop CD. This didn't receive much discussion and so it's unclear what decision was made (if any), but I guess we'll find out soon enough with just a handful of weeks to go before 12.04 Precise Pangolin is released.
Wubi.exe is released as part of the desktop CD ISO. This is fixed at release. So whenever you download the ISO you are getting the exact same one that others got on the release date... e.g. 11.04 - it's been out for a year, lots of updates, but the ISO is the same. Once you install Ubuntu 11.04, you'll be downloading 300+MB of patches. But since Wubi.exe is on the ISO it's also fixed for the duration of each cycle.
Why is this a problem? Wubi.exe typically gets limited testing during the development cycle. It doesn't get much development either - as the basic function doesn't usually change that much (11.10 was an exception to this). Most of this development tends to be after everything else is frozen, so the testing that was done early in development isn't always relevant. I could come up with other reasons, but you get the point. You're saddled with whatever bugs there are (some pretty irritating ones) - and even though many people download wubi.exe standalone, it's still fixed in stone.
So, in theory this is a great idea. We wouldn't have to live with irritating bugs, and instead of all the volunteers who support Wubi on Ubuntuforums.org having to repeat the same response 500 times, they could spend less effort making sure that the bugs are reported clearly so that a speedy fix can result.
It's still kind've nice to hand over a CD to someone and let them try out Ubuntu using Wubi, without having to download anything. I don't know how often this happens, but I guess there will be some who miss it. The question is, do you have to completely disable the CD install method to allow a stable release update to the standalone wubi.exe? Why not support both options?