There are at least two parts to the answer to your question, colordiva.

1) GSM vs. CDMA: GSM's highest level of broadband is known as HSDPA, and it's comparable to CDMA's current "fat pipe" offering, which is EvDO Rev 0. These services permit data speeds of say, 400-700kbps down and 50kbps up. (As always, "YMMV.")

In the US, Cingular's rolling out HSDPA now, but it's not available in nearly as many markets as Sprint's and VZW's EvDO.

T-Mo, also GSM, hasn't even started to deploy a high-speed network here, so it's a year or more behind Cingular. As such, T-Mo is not a good choice for packet data-intensive wireless service.

CDMA's next-gen broadband system, known as EvDO Rev A, is now starting to come online (Sprint's officially underway in a handful of markets, VZW will presumably start early in '07). It's a bit faster down and up, greatly lessens lag ("low latency"), and alows simultaneous voice and data.

Presently, no phones or PPCs support Rev A, but they'll appear in '07. Some PC cards are now available, however.

2) Devices: Theoretically, feature-set parity can exist between GSM and CDMA devices, especially at the top end, but it often doesn't. While virtually all current PPCs for CDMA support EvDO Rev 0, few GSM PPCs can handle HSDPA. The Samsung BlackJack and HTC (Hermes) 8525 are two Cingular GSM units that at least get this right.

Of course, other device-architecture, form-factor, and feature-set issues need critical evaluation as well, but this is always required.

The other consideration for GSM is frequency support. Quadband is best (850/1900Mhz US, 900/1800MHz EU, plus 2100MHz for EU broadband, where available). Incidentally, most of Europe's GSM systems still rely on a less speedy broadband implementation known as UMTS, but it's adequate.

A quick report, hope it helps.

--BAM