Yes. I never thought of that usage for them before, but I would have to say yes. If you look at other entries like the Bone Devil (Osyluth) under special abilities they are sometimes noted as "Invisibility (self only)". The Ogre Magi has no such notation, so it will work just like the spell definition I believe - both Invisibility and Gaseous Form allow targets like other creatures, so he could use these abilities on allies, not just himself.
Good question, if I am right about my answer, I never thought about the Ogre Magi using those abilities that way.
Just for historical reference, the AD&D 2.0 Ogre Mage from Monstrous Manual read under Combat: "can perform the following feats of magic: fly (for 12 turns), become invisible" and also "assume gaseous form" so these abilities were definitely personal in previous editions. Also of note, they picked up Spell Resistance: 19 in the 3.5 edition, which is pretty significant.
The 2.0 MM Edition said they could do 'Darkness (10' radius)' - in 2.0 Darkness was normally a 15' radius even the actual wizard spell name had the radius in the name. It also was cast at Range: 10 yards/level and was pretty much a total blackout in the area of effect.
In 3.5 edition, Darkness is a Range: Touch, Target: Object Touched
"This spell causes an object to radiate shadowy illumination out to a 20-foot radius. All creatures in the area gain concealment (20% miss chance). Even creatures that can normally see in such conditions (such as with darkvision or low-light vision) have the miss chance in an area shrouded in magical darkness."
So one can imagine the Ogre Mage, while invisible, quietly moving through an area and touching torch sconces 'putting the lights out' before a big assault begins.