Frost dk as it CURRENTLY stands on live servers is a lot of fun, a LOT. I think Any spec is good for dks, but frost is the most fun given that the sheer amount of control you have over opponents. You get chill blains, free cost interrupts, lichborne for fear breaking, deathgrips(you can even spec into unholy for reduced cooldown on dg) hungering cold spam, howling blasts frost strikes pewpewpew. I have often just kited people to death running big circles around them lol its a lot of fun. Currently you can still spec into blood tree far enough to get all the two hander talents AND rune tap/imp rune tap. Although this is going away in cataclysm, right now its very strong with glyph if you get your team in the same group its a BIG party heal every 30 seconds, coupled with all the control, if you get in trouble start kiting/cc and heal up then zerg back in. Fun times indeed!

As for the "frost BOOM spec" lol wtf are you talking about :P I've been playing my dks since wotlk release and i've never heard of a frost boom spec ! :P lolol