I've added some hyperlinks to a test report, using the following code in the 'action' section of the text box properties:
="void(window.open('http://crm.preqin.com/useradmin/Contact.aspx?ContactID=" & Fields!contact_id.Value & "','_blank'))"
I've also tried the above with _newtab.
In IE(9) I have the tabbed browsing settings 'Always open popups in a new tab' and 'Open links from other programs in: a new tab in the current window'
The report still opens a new IE Window, is there any way to get around this? It's fine in Firefox but the Report Manager doesn't really play nice in Firefox does it!