PA31 pilot experiences a NMAC at 11;000 FT with a B737 climbing off MCO. The controller did not tell either pilot to maintain visual separation.

Narrative

We were level at 11;000 southeast bound on an IFR flight plan crossing the Orlando Class B airspace. We were being vectored 'Overtop MCO.' A B737 was climbing out of MCO; southwest bound climbing off the runway. I was asked if I had him in sight; 'I would like to keep him climbing.' I stated I had the traffic insight. It was night and in clear conditions; it was easy to see the lights on a B737. The Controller told the B737 to climb and maintain 16;000 then said; 'the B737 will be crossing your altitude.' I never said I would maintain visual separation; I just said I had him insight. Next thing I knew; they were a collision factor. Our TAS system sounded and I told the Controller; 'I don't think this will work.' Controller said turn left (into the path of the B737) I started to roll left; but rolled the wings level. Next the B737 crew stated they had an 'RA' and took action; Crossing 300-400 FT below us. Why wasn't the B737 turned 10 degrees right or vectored behind us and then climbed? Why was he issued a climb without having a visual on us? I had no way to get away. After the incident; I asked the Controller for the TRACON phone number. When I got to my destination I called. The person who answered knew all about the incident. All I got out was my name and he asked; 'were you just in the Navajo?' I said yes. He said I recognize your voice from the tapes. He said they have reviewed the tapes and [said that] the Controller should not have issued a visual when he did. He also said the B737 climbed at a slower rate than normal. Two things to correct.... There needs to be a better route (airway) over Orlando from the northwest to the southeast. I think the Controllers need to leave planes on the airways; rather than vector them and allow strong winds aloft to cause drift (like today).