Can Visual Studio 2012 be installed side-by-side w/ Visual Studio 2010?
As Reigo said, yes. Here's the link to the official Microsoft page with the information Reigo provided, and more details: http://msdn.microsoft.com/en-us/library/ms246609%28v=VS.110%29.aspx
The .net 4.5 release is an In-place upgrade.
This means that the binaries for .net 4.0 will be REPLACED by the binaries for .net 4.5.
Microsoft has attempted to mitigate the problems this causes by making a "Target .net 4.0" feature. But this is very different from the targeting previous versions of .net (which have been side by side since .net 2.0).
Because it is a in-place upgrade, "Target .net 4.0" cannot really target it. The best they can do is try to manually remove some "features". They have done this (Scott Hanselman had a blog post covering this).
But don't let this fool you into thinking you are really using .net 4.0. Any bugs fixed by .net 4.5 will be fixed on your development machine and not for your .net 4.0 users.
So if you are developing an application "targeting .net 4.0" and you have .net 4.5 installed then you are at risk. If you accidentally use a fixed bug, it will not break for you while debugging.
When you deploy your app to a machine running only .net 4.0 (ie windows xp) then those bugs are not fixed for your user.
For all intents and purposes, those fixed bugs are now "Hidden Bugs" (for developers that still need to target .net 4.0.
The best part is that it does not matter if you use VS 2010 or VS 2012. Once .net 4.5 is installed the bugs are hidden.
See this post for more details: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/c05a8c02-de67-47a9-b4ed-fd8b622a7e4a/
I've been burned badly by VS betas, never not had a nasty problem getting them uninstalled. Microsoft makes fine software but the installer seems to always be the very last thing taken care of. Problems I've seen is the uninstall not removing components that then screws up the retail edition and the installer not counting on other installed Microsoft products and destroying their configuration.
This one is far before a beta, do not install it on a machine you need to get your job done. Which pretty much precludes having VS2008 installed. VM is fine of course.
I installed the RC yesterday, and found the following:
It causes VS2010 to freeze when running unit tests (this can be worked around by using 2012, or mstest on the command line to run your unit tests)
It causes VS2010 not to be able to compile C++ projects, failing with a link error. Even after uninstalling VS2012 RC, this problem still persists... so I'd advise strongly against installing it right now