Back in April I commented on incompatibilities with various Web CMS tool interfaces and IE7 in Microsoft Vista. Now, 4 months later I am busy researching the upcoming 12th edition of the Web CMS Report, and still many vendors (e.g., CoreMedia, e-Spirit, eZ Systems, Vignette) do not yet fully support IE7-on-Vista, and in some cases (e.g., Synkron) seem to have no near-term plans to do so.
Interestingly when I interview end-users or consultancies they frequently bring up lack of Vista support as an increasing annoyance, in particular for editors (who frequently must work from home), but when I speak to vendors they never mention Vista support, unless specifically asked. Instead the vendors I've interviewed are much more keen to talk about "social software," blogging, and tagclouds. Supporting Vista may not be "hot stuff," but it is surely important as home users upgrade their PCs. [Update, September 4: CoreMedia points out that they already partially support IE7/Vista. Added Synkron as their plans for support are still in the dark]