Note to Self: (
sorry, couldn't resist...) I don't think a planet would sneak up on us because of technology to find it or even see it, but it seems, given the almost total lack of mainstream info and interest in Elenin, (I've lived through a number of cometary visits over the decades and ALL of them got far more coverage and interest than Elenin) there may be something strange happening with the reporting side of their discoveries and observations.
Try looking at Eelnin info online - it is amazing how little official information is available - try just finding out the actual size of it... The alternative sites have LOTSA guesses but the official ones can't tell you if it is 1km or 1000kms across.
Now go look up Comet Honda - due at aphelion at end of August it's coming MUCH closer than Elenin - last I saw it was like 9 million kms. Heard much about it? No, neither have I.
The reporting media seem to have decided we should not hear about such things - one has to wonder why so many people across the world have all decided to go quiet about incoming objects.
And there have been reports over the past few decades of an infra-red source out there - the preots seem to imply it is getting closer, although I don't think from the little I've seen that it could possibly be here by end of 2012. But the reports can still be read, even if they don't seem to get updated.