Did you have a requirement of getting last date of the month by passing any date. I can remember I had this requirement during SQL Server 2000 days, in a HR system.
If you search for this in Google followings are the results.
There are around 2,350,000 results!. In these results, there you might they have used DATEDIFF and DATEADD functions.
With Denali CTP3 (not sure whether this was there in CTP1) new function called EOMonth is included. Now it is simply matter of passing date.
You can see the a syntax in the following image. Point to note here is there is no execution plan differences between this version and the previous. So only difference will be the usability,