On the Windows platform at least, there is certainly a _need_ for custom controls that know how to render latex and/or mathml. I recently did a fairly exhaustive search for exactly that and was rather shocked to dicover that there was absolutely _nothing_ that would do the job. Specifically, if you built a native WPF/Silverlight widget that was was capable of rendering latex/mathml it would certainly fill a gap because at present, as far as I know, nothing like this exists. Yes, there are custom applications of course that do this such as Mathematica, Maple etc. but nothing that can be reused by an ISV to build their own math-oriented applications.