I would like to know how I can use VS 2010 to write custom WebParts for SharePoint 2007? VS 2010 does not give you any project templates for SharePoint 2007. Has anyone used VS 2010 for SharePoint 2007 development?
The best Visual Studio plugin I ever used for SP2007 development, SPVisualDev, is avaliable for Visual Studio 2010:
Visual Studio 2010 is now supported. Note that this add-in is only intended to be used for MOSS 2007 / WSS 3.0 development and not for SP 2010.
SPVisualDev is a great tool, which natively allows remote debugging on virtual machine, and also it support model of quick, ASP.Net-like deployment of SharePoint mapped files, on-build deployment of assembly to GAC, and also it provides very convenient and flexible interface to deal with features (and all this - remotely, and plus remote debugging).
Actually, I wouldn't say that the current native SharePoint Developer Tools from Microsoft, even with great bunch of improvements from CKS:Dev, is better than SPVisualDev. That's pity, but I'm afraid that's truth :(
We apologize that Visual Studio 2010 Developer tools will only be available for SharePoint 2010
I am not sure if VSeWSS 1.3 to work with VS2010, but you're probably better off using STSDev or WSPBuilder for 2007 development anyway, which could probably be made to work with VS2010 if they don't already.
I found this useful guide: http://tallday.wordpress.com/2010/12/16/developing-sharepoint-2007-webparts-using-visual-studio-2010/
I have not tried it, but it does save having to install both Visual Studios side by side.