is_post_type() within the loop?

What you you need is is_singular():

if (is_singular('photogallery')) {
    # Do some stuff.
} else {
    # Do some other stuff.
}

If you’re inside the loop and want to know about a specific post, then you’ll want to look at get_post_type(). is_singular() refers to the loop as a whole.

Ouch. Apologies for the misinformation. Andrew Nacin is correct.

So, the correct example would be:

if (get_post_type() == 'photogallery') {
    # Do some stuff.
} else {
    # Do some other stuff.
}

Awesome. Just what I needed right now. Thank you Andrew, thank you demetris. You guys rock!