Fr Z gave me the idea for this, I must admit...
Having surveyed Christ's faithful, or at least such persons (all twenty!) as voted on my blog-side poll, it appears that 70% think we should petition the Holy See to permit the wearing of blue vestments on Marian feasts. This privilege currently applies in certain parts of the world, notably formerly Spanish lands and some other places (Bavaria is one); it originally appertained to the feast (and former octave) of the Immaculate Conception, but seems to have been extended to other feasts of Our Lady.
Interestingly - directly contrary to the rebellious advice tendered by avant-garde liturgists - only 30% thought the current violet or purple of Advent ought be replaced by blue. (I must admit, I think blue for Advent would be nice, particularly as it is such a Marian season of holy expectation for Christ's coming, partly reliving His past advent as our Redeemer, partly living His present advent in secret grace and the Sacraments as our Saviour, partly keeping watch for His definitive Return in glory as our Judge.)
The sensus fidelium seems manifest... but of course it is for the pastors of the Church to decide.
So, who's going to draw up the Latin petition? Patricius, are you out there?