Would be useful.
That info is available from http://wuprop.boinc-af.org/results/delai.py, so it's collected, however it's not presented; you have to search for it and that's a lot of work for end users.
Some projects have the same app for several OS's, whereas some projects only have apps for one or two Operating Systems. For example, GPUGrid has GPU apps for Windows and Linux, but not Mac or Android.
So it would be useful to know up front; if you want to crunch a new project/app you don't know if it's available for your operating system(s) or not, unless you go to the project site and check the apps and the server_status pages, which takes a bit of effort.
Perhaps VM's and MT (Multi Thread) apps could be denoted too, though most tell you that info in the app name. Ditto for NCI (Non Compute Intensive) apps.
As far as I'm aware there are no apps for both CPU and GPU; all GPU apps denote they are for GPU's and usually stipulate AMD or NV.
Ideally there would be a column/columns showing the number of tasks ready to send, against each projects apps. That might be better on a separate page or on a stats site but none are doing this yet. Closest just tells you if there is work available or not. Problem with that is some projects always seem to have at least 1 or 2 WU's sitting ready to be sent, when there isn't actually any.