Citing a desire to "deliver a high-quality product," Microsoft's Macintosh Business Unit said Thursday that Office 2008 for Mac will not be ready before the end of the year as previously planned. Instead, the long-awaited product will reach customers in mid-January 2008.

The last major release of Office for Mac OS X came in 2004, and customers have been clamoring for an update since the 2006 switch to Intel-based Macs, as Office still requires use of the Rosetta emulation layer that slows the software down. For a brief while, there was a question whether Microsoft would even continue development of Office for Mac.

The 2008 release is slated to bring the product up to date with its Windows counterpart, adding the new "Ribbon" interface and support for Microsoft's new Open XML formats. At the moment, files created in Office 2007 on Windows in the default format are not readable on the Mac without a separate plug-in.

But the major changes have brought about development delays, leading to the "business decision" to push the release back.

"We had hoped to deliver the product in the second half of 2007 and as you know might imagine, this was a tough slip for us. Moving RTM to December means you, our customers, won’t have our product this year, and I am very clear a lot of folks are eagerly awaiting Office 2008," said Craig Eisler, General Manager of the MacBU.

"We’re in an “all hands on deck” mode right now to ensure Office 2008 gets finished on time, and so you will not see final versions of our RDC client or file format converters until sometime after we ship Office," added Eisler.

Microsoft promised to offer customers a series of "sneak peeks" at Office 2008 for Mac starting in September, which will show off the update's features and functionality. "We’re successfully driving toward our internal goal to RTM in mid-December 2007, and believe our customers will be very pleased with the finished product."