I am currently working on a simple Silverlight app that will allow people to upload an image, crop, resize and rotate it and then load it via a webservice to a CMS.

Cropping and resizing is done, however rotation is causing some problems. The image gets cropped and is off centre after the rotation.

WriteableBitmap wb = new WriteableBitmap(destWidth, destHeight);

RotateTransform rt = new RotateTransform();
rt.Angle = 90;
rt.CenterX = width/2;
rt.CenterY = height/2;

//Draw to the Writeable Bitmap
Image tempImage2 = new Image();
tempImage2.Width = width;
tempImage2.Height = height;
tempImage2.Source = rawImage;

wb.Render(tempImage2,rt);
wb.Invalidate();
rawImage = wb;

message.Text = "h:" + rawImage.PixelHeight.ToString();
message.Text += ":w:" + rawImage.PixelWidth.ToString();

//Finally set the Image back
MyImage.Source = wb;
MyImage.Width = destWidth;
MyImage.Height = destHeight;

The code above only needs to rotate by 90° at this time so I'm just setting destWidth and destHeight to the height and width of the original image.