Wieters will not be starting opening day. He will likely come up during the season depending on how he does in AAA. Orioles arent about to risk damaging their best prospect by rushing him as many "top prospects" have flamed out when rushed and failed their first call up. They traded Ramon because its not like he has been that good lately and their 09 success or failure isnt going to be determined by having him around so they got what they could (before he was walking anyway I believe? not sure on that offhand but though I saw he was a FA after this year). Orioles realize they arent contending this year but that doesnt mean you throw the kid to the wolves. Theres so many fill-in options available to be a placeholder and/or mentor him when he does come up. Amazing to have seen him go in 10th and 12th rounds in big mock drafts. Can't imagine why an owner who is taking the process seriously would waste a high pick on him, let alone people who are going to in a real draft. But obviously they must think that highly of him. For every Soto there is a Towles, for an analogy. Many people were very high on both of them last year and some expensive investments were made in each. One paid off and one didnt. I know Wieters' pedigree is higher than either but all 3 were young fantasy catcher players with the hype factor attached.
IMO if you want and believe in him I can only see using a late round flyer on him, even in keeper formats. Let someone else spend the high investment. Even if he were to work out and be a decent fantasy catcher option right away if you are spending a 10th rounder on him thats not much of a return on investment which is a big factor in getting the edge on your opponents in leagues.
As far as the discussion about the O's holding him back in regards to his contract, Angelos wants to get back to winning and if they like what they see out of him in AAA I dont think they will hold him back for contract implications. He will be brought up when ready so he can start to gel with the rest of the team especially the other younger players and pitcher to start their build back towards possible contention in say 2011.
On a side note I have a wager with a huge weiters fan. He bet he would play in 100 MLB games this year. Considering even the best established catchers usually play in that 140 range at the Max, Im liking my odds

And if anyone is curious personally I LOVE him and his potential, big fan much in the same way I was following Lincecum as he was drafted and coming up (Easily my favorite player) but I never spent more than a FA pick on him either in 2007 and through that was fortunate to have him in some leagues including keepers.
"I'm the man with the ball. I'm the man who can throw it faster than F***. So that's why I'm better than anyone in the world." - Kenny Powers