My company develops an updater/patcher. The updater is open source (wyUpdate) and the update creator is commercial (wyBuild).
You make a few good points in your post. We get a lot of customers trying to solve the very problems you describe. Auto updating in particular is an exceedingly hard problem to solve.
Besides all of the immediately obvious technical considerations (Self updating, inter-process communication, update rollback on failure) there are many problems that developers don't think about until it's too late (admin rights, Vista/7 UAC).
You might be interested in the series of posts I've been writing on creating an updater from scratch: http://wyday.com/blog/
You make a few good points in your post. We get a lot of customers trying to solve the very problems you describe. Auto updating in particular is an exceedingly hard problem to solve.
Besides all of the immediately obvious technical considerations (Self updating, inter-process communication, update rollback on failure) there are many problems that developers don't think about until it's too late (admin rights, Vista/7 UAC).
You might be interested in the series of posts I've been writing on creating an updater from scratch: http://wyday.com/blog/