The market for the "entry-level DSLR" has skewed significantly since the implementation of HD video into the many new cameras coming out lately. What I see has happened is that the entry-level market slot has been widened by manufacturers with the various implementations of video and the attempts to get some more advanced features packed into their lowest priced DSLRs.
To me the big difference between entry-level and mid range come down to a few distinct factors/features such as higher fps shooting, better arranged direct-access buttons, dual control wheels, top-mounted LCD, more solid build, etc.
So -- from that point of view the 550D still is entry-level to me -- although it's at the higher end of the entry-level, it still shoots well below 4fps, - which makes it more difficult to use for high motion shooting like sporting events, etc. What I would not use to define entry-vs-mid level cameras is mp count. Some people would, but not everyone.
Hope this helps breach the divide.