Keep in mind Microsoft didn't really buy Sidekick. That is T-Mobile's property. Microsoft bought Danger which makes the OS and runs the network the Sidekick connects to. T-Mobile still will have complete control over the hardware and what the phone does. Most Sidekicks are manufactured by Sharp (with the flop exception for the Motorola Sidekick Slide.)
like i said in the other thread, if would be great if microsoft uses this to push for the next generation of mobile gaming, a sidekick that has similar power to the psp but uses the 3g network for wireless multiplayer (halo mobile?)