The part that I don't get about Sharia banking (and this is something that I've brought up before with respect to some other behaviors I've observed in some Muslims) is that much of it seems to be simply semantic hair-splitting as a way of getting around the letter of Allah's rules, rather than trying to follow the spirit of them as well.
For instance, Sharia forbids charging interest, so a Sharia bank account cannot be interest-bearing. Instead, the principle in the account is used to buy some portion of an asset (held by the bank), which the bank retains use of, and therefore the account-holder is entitled to "rent" on the portion of the asset that he owns.
So where a traditional savings account with $1000 in it might earn 3% APY, and thus have $1030 in it by the end of the year, a Sharia savings account with $1000 in it might therefore "own" a small portion of the bank building, and the rent on that portion of the bank building might, say, equate to $30/year. So at the end of the year, the account would have $1030 in it.
This sort of disingenuous reasoning seems to be on the same level as a Christian reading the commandment "Thou shalt not steal" and deciding that "borrowing for an indefinitely long time without first obtaining permission" is OK, because it isn't, technically, theft.
-BP