If you take your shiraz or pinot noir seriously you won’t need us to tell you that red wine needs to breathe to be at it’s best.  Allowing the wine to react with the air before you drink it enhances the flavours and makes for a smoother finish.  In the past this has meant uncorking and/or decanting the bottle and leaving it for hours, or at least spinning your glass around frantically in the manner of Oz Clarke.