I was searching the connect site for before posting an issue the other day and came across this
SSMS : Allow support for AddIns as in Visual Studio
https://connect.microsoft.com/SQLServer/feedback/ViewFeedback.aspx?FeedbackID=265567
Which I have thought would be a good idea since I first started work on BIDS Helper. So if you think it would be a good idea too, please follow the link and add your vote.
I don't think there is any chance of this feature making it into the release of SQL Server 2008, so maybe the next version (or a service pack if we are lucky).