Philosoraptor: If it's almost, already, always, and altogether, why is it all right to say "alright" is slang?
Business Cat: "All Right" = 283,000,000; "Alright" = 168,000,000 Google Hits; Trust Google (This Time)
English Error Echidna: All Right, Already; It May Look Awkward, But "All Right" is All Right
For more on ALL RIGHT, ALL READY and ALL TOGETHER, see Grammar Girl
The slang term “alright” is always slang.