You can check if an item is a media item by using:
item.Paths.IsMediaItem
It checks if ‘media library’ is part of the item’s path.
(I had a multilist of items that could be either regular content items or media items, and needed to loop through and render a link for each one. Because you use different methods to render a MediaItem link (MediaManager.GetMediaUrl()) and regular item link (LinkManager.GetImageUrl()), I needed to know what type the item was.)
MH Welander 
Hi Martina,
Sitecore.Data.ItemPath — items.Paths is an instance of this class — has another similar property for content items: IsContentItem. This helps calling code ascertain if the item is a descendant of /sitecore/content/.
Mike
Hi,
The property IsMediaItem just checks if the path starts with “/sitecore/media library/”. So a media folder within the media library is also considered a MediaItem. I handled this by also checking on TemplateID:
item.Paths.IsMediaItem && item.TemplateID != TemplateIDs.MediaFolder
(please ignore previous comment)
Hi,
The property IsMediaItem just checks if the path starts with “/sitecore/media library/”. So a media folder within the media library is also considered a MediaItem. I handled this by also checking on TemplateID:
item.Paths.IsMediaItem && item.TemplateID != TemplateIDs.MediaFolder