Apple’s promised “end of October” launch window for its iTunes Match service came and went without any any word from the company, and without the release of iTunes 10.5.1 — a necessary update to take advantage of the service.

iTunes Match is part of Apple’s iCloud service. The US$24.99 a year add-on allows users to match music in their local library not purchased from iTunes to Apple’s own servers, and then access that content from any device with their iTunes credentials.

iTunes Match: MIA

Apple has been testing iTunes Match with iOS developers, but earlier in October opened registration to the public even though they couldn’t take advantage of the service yet. At the time, Apple said that iTunes Match would active for iCloud subscribers by the end of the month.

iTunes Match has been touted as an iCloud feature ever since Apple first showed off the MobileMe replacement earlier this year. When the service officially launched along side the release of iOS 5, iTunes Match was conspicuously missing and said to still be in beta testing.

The bad news for developers that have been testing iTunes Match is that the iTunes 10.5.1 beta they’ve been using expired today, potentially leaving them without an easy way to get at their music libraries.

Apple hasn’t said exactly why its October deadline slipped, but it seems likely the company felt it wasn’t quite ready for public use yet. The lack of an iTumes Match does, however, finally give the media and analysts a legit missed deadline to talk about instead of rumored launches that never materialize.