Is there a way to hide pictures from being shown in Gallery How can I hide a jpeg image in Android Gallery?
or is there a way to hide a folder of pictures for Gallery only?
If you add a file with the name .nomedia (note the period at the beginning) to the folder, the automatic media scanner will skip that folder in the future. Thus no images from there will appear in the Gallery.

You can do this by tethering to your computer or by using one of the several folder-browsing apps in the Play Store (e.g., ES File Explorer, ASTRO).