LIVE coverage beginning at 4 p.m. ET.

Preview:

The big question: How many Macs did Apple sell? The Street expects sales of 2.0 million, but we've seen estimates as high as 2.2 million (RBC's Mike Abramsky) and whisper numbers up to 2.3 million. Anything below 2.0 million would be disappointing. But anything over 2.1 million Macs would be "a significant positive," says Piper Jaffray analyst Gene Munster. Selling 2.1 million Macs represents 38% year-over-year growth, significantly higher than the average 26% y/y Q3 growth the last three years.

Also critical: guidance. In January, when Apple demolished its Q1 numbers, the stock still tanked 11% after-hours, thanks in part to weaker-than-expected guidance. The Street expects Apple to guide to $7.15 billion of revenue and $1.10 EPS for Q3, but Apple is known for conservative guidance, often guiding below consensus. Anything below $7 billion/$1.05 could be disappointing, according to AmTech's Shaw Wu, who downgraded the stock yesterday.

iPod and iPhone unit sales will be interesting, but not essential. Investors already know that iPod growth has slowed -- and Apple could easily sell fewer iPods during Q2 2008 than it did in Q2 2007. And while the iPhone makes for great conversation, it's still too small to make a dent in Apple's quarterly results. It will, however, become more important later this year (when the 3G version comes out) and next year.

Key metrics:

Revenue: $6.95 billion consensus (32% y/y growth), $7.1-7.2 billion whisper numbers (AmTech)

EPS: $1.07 consensus, $1.25-1.30 whispers (AmTech)

Mac sales: 2.0 million units consensus, 2.2-2.3 million units whispers (AmTech)

iPod sales: ~10 million (down 5% y/y) Street sentiment (Piper)

iPhone sales: 1.7 million consensus (Piper), 1.8 million bull case (RBC), above 2.0 million a surprise (Piper)

Q3 guidance: $7.15 billion revenue consensus, $7 billion lowball whisper; $1.10 EPS consensus, $1.05 lowball whisper (AmTech)

See Also: RBC: Apple's Mac Thriving In Tough Market, AAPL To $190