From recent memory in South Asia...

Kargil 1999

Fact: Some Indian High-Altitude Warfare School instructors led assaults on sheer-cliffs defended by Pakistani Special Service Group commandos (and allied Islamic terrorists); Guns of Navarone-style cliff assaults ~ but at -20 degree C temperature. While HAWS isn't technically "Special Forces", it is one of the schools "Special Forces" have to pass through and its instructors have spec ops type qualification.

Rumour: The "Special Forces" battallion assigned to Northern Command was mainly tasked with cutting off supply lines in the more sensitive parts of the border (i.e where you might have had to cross the LoC). Mostly they carried out holding actions on resupply convoys, blew-up ammo dumps etc. In these altitudes its quite likely that most of the convoys had some spec operators. It was a time-critical mission to prevent them from being resupplied and prevent prolonging the fight until UN forced a ceasefire (as was Gen. Musharaff's calculation). Towards the end of the conflict they were retasked for hunter-killer missions - either stopping exfiltration guides from SSG comming in, or holding-down fleeing infiltrators for either the artillery or the pursuing regulars to finish them off.

Soviet-Afghan War

Caravan-Hunters (Spetnaz) vs. SSG: SSG personnel from Frontier Force Regiment and other Pathan units occassionally guided supply convoys for Afghan Mujs when it suited Pakistani interests in not skimming off of the military aid. The cat-and-mouse game played there has probably made Pakistani SSG one of the best covert infil-exfil guides for irregular/guerrilla groups around the world.

1982, Falklands, the SAS vs SBS, it was an accident though, unforunatly one shaky boat died

Modern special ops?  I don't know, but there's been many engagements between what amounted to an elite v. elite.  Among them:

Sniper v. sniper-American riflemen v. British riflemen at New Orleans (the British had a battalion of the green jacketed 95th there)-Light cavalry v. light cavalry-Paratroopers v. paratroopers-OSS/SOE agents v. Gestapo-SOG recon teams v. counter recon teams specifically fielded to eliminate SOG teams.

Probably others too.

Recently, and this is gospel, Armenian special combat trademark attorney brigade versus Georgian spetznaz copyright attorney forces.  I hear the IP quibbling violated many conventions of warfare as well as several EU environmental regs concerning garlic emissions and flatulence.  Perhaps it’s just a rumor, we’ll probably never know for sure since it’s black force on black force conflict . . .

v^2

Generally its not a practice for various nation's UW units to seek each other out and "Face Off". If you could locate a UW unit and had a chance to engage them it would be far better to bring to bear your numerically superior and firepower superior conventional assets who with increase SA would utterly destroy a small unit most likely. Thats why UW operations are so big on stealth because thats their greatest weapon. Having said that...

...A lot of the various terrorist operators out there are quite skilled and very much qualify as Spec Ops when you consider the small unit tactics and individual skill sets necessary for their operations. So I would consider a lot of the past and present anti/counter-terrorist operations to be Spec Ops vs Spec Ops.

Just think about the vast array of skill sets necessary to hijack a plane, power plant, conduct an assassination, bombing or hostage taking. Terrorist who have carried these operations out are very skilled and present very tough targets. They may not use the latest version of whatever H&K is pushing, they may not wear oakleys and they may not even be literate but their operational successes are a testament to what happens if you under estimate them. Spec Ops is so much more than just room clearing. Anyway thats my 2 cents.

DA

Could you define what you mean by "Special Forces Work"? Thats a very broad statement and most likely handled by MPs, Police and security personel if you are referring to the types of operations that are more popularly known.