Wall Street analysts continue to find confusion in their attempts to analyze cutting-edge technology company, Apple.

Despite Apple stock reaching a three-year high on Friday, SG Cowen analyst Richard Chu wrote: "Apple's numerous product/market initiatives are all exciting and keep investors wondering what Apple will pull next out of Steve Jobs' sleeve," the Globe and Mail reports.

"We find it difficult to document how this will collectively translate into a sustainable higher margin model," he added.

Smith Barney analyst Richard Gardner rates Apple stock as a 'sell', and has a target stock price of $23. Responding to Apple's Q1 financials, the analyst observed "lower-than-expected" Power Mac G5 sales, which he said: "raise concerns about the sustainability of recent Power Mac shipment levels."

Speaking to Morgan Stanley's Semiconductor and Systems Conference last week, chief financial officer Fred Anderson asserted Apple's expectation that it would sell 200,000 Power Mac G5s per quarter, while the product line remained fresh – a target Apple met in the last quarter. He implied that Apple would upgrade the Power Mac range to continue to meet such expectations.

"We think we can sustain around 200,000 unit sales of Power Macs per quarter during a given product's lifecycle," he said.

Apple confirmed yesterday that its Xserve G5 servers would ship this month, rather than the February promised at Macworld Expo January.

That news emerged as UK resellers told Macworld of their expectation that new Power Mac G5s would soon ship to the channel.