HTC just released the sourcecode for the kernels on their Aria, Desire Z, Desire HD and myTouch 4G. These devices have had their kernels released previously so today’s release represents updates, bug-fixes, and improvements.
The kernel is “the central component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel’s responsibilities include managing the system’s resources (the communication between hardware and software components). Usually as a basic component of an operating system, a kernel can provide the lowest-level abstraction layer for the resources (especially processors and I/O devices) that application software must control to perform its function. It typically makes these facilities available to application processes through inter-process communication mechanisms and system calls.” (Wikipedia)
All we need to do is wait for custom ROM developers to cook these updates into their custom ROMs and custom kernels.