While many have said Apple's iPhone would immediately spell trouble for RIM's BlackBerry, it's not happening yet according to the latest research.

First quarter sales data compiled by research firm IDC indicate that sales of the BlackBerry increased during the first three months of 2008, while sales of the iPhone decreased.

While some may be quick to deduce that this means trouble for the iPhone, there are probably a few factors contributing to the decline. First, the quarter follows the holiday season which was a blockbuster for Apple.

Second, with the talk of a 3G iPhone, some may be holding off their purchase until it is released. If this is to be believed, the quarter which just ended could look superficially worse than the first.

Apple is widely expected to launch the iPhone later this month, which will place the device's sales in the third calendar quarter.

In terms of numbers, RIM garnered a 44.5% share, up from 35.1% in the previous quarter. Apple took a 19.2% share, down from 26.7%.

Another bright spot in the numbers was Palm. The venerable smartphone provider -- and arguably the pioneer of the smartphone market -- nearly doubled its share to 13.4%, up from 7.9% last quarter. This could be seen as validation of the company's strategy regarding the Centro.

While the Centro debuted last year, it was only on the Sprint network. In February, the company released versions for other carriers, and it looks like consumers responded well if IDC's numbers are to be believed.

Rounding out the top five was Samsung at 8.6%, up from 5.1%; and HTC, down to 4.1% from 7.9% previously.