Tried a nightly build with Resharper 7 and ran into two issues.
1. It looks like R# uses MetadataAttributeValue differently in 7. The plugin code assumes that only the MetadataAttributeValue.Value property is used and is never null, but now the ValuesArray property is used instead for params parameters. Caused a NullReferenceException.
2. Might be an old issue, but attributes with params parameters doesn't work. An example of this is the MultipleCulture attribute. Removing the special handling of params parameters from the plugin seems to fix this.
I've attached two patches where I've attempted to fix these two issues, no idea if they break something else. But with them applied the R# plugin works for me at least.