I have the Canon EF 8-15mm F4L and use it with a 5D MKII and PS's Adaptive Wide Angle Filter and Fisheye Hemi plugin, which works quite well. You can get similar correction in LR using the Canon EF 15mm F2.8 lens profile's Distortion slider, but there will be some fall-off in image sharpness in the corrected areas. This can be partially corrected using a Radial filter with the Sharpness slider. There are also other Canon 15mm and an 8-15mm profile available using the Adobe Lens Profile Downloader:
http://www.adobe.com/support/downloads/detail.jsp?ftpID=5492
http://www.adobe.com/support/downloads/product.jsp?product=192&platform=Macintosh
You can also use the open source Hugin application: