At the company I work for we are planning several projects that are scheduled to be released late in 2010. We currently have production applications running in all previous versions of .Net. When the development of the projects start, I would like to consider utilising .Net 4.0. Before this could occur, I would have to feel comfortable proposing the idea and would also have to convince management. I am looking for opinions of starting a new project with the .Net 4.0 framework as well as pointers for convincing management if the opinion is that the newest .Net framework should be used. One thing to consider is the tools we currently use (Telerik and EntitySpaces) and if there would be any issues using these tools with the .Net 4.0 framework. Both of the mentioned vendors claim there products will be ready to use with .Net 4 when the product is released, but I know there is no guarantee. I look forward to everyone's feedback. I know research on this topic would not be complete without posting the situation on SO :)
Get your hands on a beta or an RC and see what's changed in 4.0.
Test the tools you currently use for compatibility: know how well they work, when they are expected to be 100%, etc.
Being smart on it already when it comes time to propose working with the new framework will go a long way toward convincing management that you're in a position to take advantage of the new features.
No reason not to. Folks like Telerik and ES will be ready before you are.
In the end, there aren't that many breaking changes. The tooling is superior. And you have options that don't exist in 3.5.
In general, I want all fresh starts to be in the latest and greatest. That's where the community effort is. And if a tool saves a developer an hour a week, it's worth the cost.
.NET 4 is in release candidate stage and very stable in my opinion. It also has a GoLive agreement which means it's supported in it's current state. It will be released this Spring so it will be RTM by the time you are ready to deploy. Having said that obviously you and the stakeholders must make the ultimate decision but I think it's a safe choice. Also because it's a new CLR version, migrating the app to 4.0 later could very well have breaking changes so starting with the 4.0 runtime would be a better idea than migrating later on in the development when those changes could impact your deadline.
I would have to feel comfortable proposing the idea and would also have to convince management
Not only do you need to be comfortable with the idea, but you will need to be an advocate. What are the risks, the costs (not only for software aquisition, but training and ramp-up time for other team members) and the benefits? Do your research. Get your hands-on time with 4.0. Ask yourself, "How would I approach this application differently in 4.0?"
Build a compelling pitch. Until you do, don't expect management to lead the drive to upgrade.
You also need to consider the time it will take for .NET 4 to become widespread - it won't be immediate, except in the developer community. If you are building a redistributable application on .NET 4, potential customers will need the latest runtime installed. This is not so much an issue for server-side work, but even that may be an issue.
If you are planning an application that will be out some time after .NET 4 is released, then that may work for you. Without knowing how MS are planning to distribute the v4 runtime, I suspect it will be a while before it is broad enough to be depended on.