I know it's a long time since this question was asked, but I figured I'd put the answer out in Google-land...
I noticed this on v8.1. I don't have any experience with v8.0.
I was informed by SwiftPage that this was registered as Defect 14095529 and will be fixed in v8.2. There are currently no plans for creating a hot fix before 8.2 release.
Funny thing though, the partner portal does display the account groups and it's v8.0. Somehow they got it to work...
Supplemental: I also have code in our 7.5.4 Customer Portal that loops through the GroupInfo items (retrieved using the GroupContextService) in order to hide/unhide groups based on localization (using the .IsHidden property). This no longer works in v8.1. It seems that this has partially been replaced with JavaScript and doesn't respect the GroupInfo definition.
