<p>Is there a mode, some switch or a programmatic way that I can ask MSBuild to display or output it's calculated dependencies for a given build file?</p>

<p><strong>Some background</strong> - 
I have a large project that requires splitting up to speed up the build time and want to remove the slow changing infrastructure code into it's own release area.  Not all of the information is contained in the build file itself, as some sub-projects are referenced by their vcproj or csproj files.</p>

<p>I'd really like to see what MSBuild thinks needs doing (either worse-case [rebuild all] and perhaps for a make) without actually doing the rebuild.</p>

The
MSBuild Profiler
project should be able to help you in seeing where time is being taken on the build.  It doesn't directly show dependencies.  With or without build dependencies, just profiling the builds can probably give some insight and help speed up the process.
I did just come across this application, but I have not used it myself yet,
Dependency Visualizer
that looks to have just added MSBuild-compatible project files.  There have also been posts about doing this previously, but no code (see
A
,
B
).