Never rely on hoopshype; they're garbage for salary information.
Looking at more reliable sites, like shamsports and this
google spreadsheet, it looks like Rasheed counts about $491,109 on this year's cap.
We don't know whether Rasheed's retirement was formal or informal. However, we do know that it was reported that he agreed to a buyout of his deal. How buyouts work is that whatever amount the team agrees to pay a guy is divided equally by the number of years left on a guy's contract. That amount is then applied to each year that was remaining on the contract.
Here, Rasheed had two years left on his deal. That means that, for whatever reason, the buyout amount her agreed to was around $982k, if the reported cap hit this year is accurate. It's hard to say why the team and Rasheed came up with that odd ball number. Maybe Rasheed had already been paid part of his 2011 salary by the time he walked away, and didn't want to give it back, so they agreed to a buyout. It could be it was just courtesy money to keep Rasheed from formally retiring while we tried to trade his contract (although the $982 figure is still a mystery.) Whatever the case, it was a small amount, but we still have it on our cap through this year.
Also, clover is correct: you can't trade retired or bought out contracts.