Feb 27 2010 - Saturday afternoon departures (in season) from Beatrix airport in Aruba can be a nightmare. They are many US flights departing in the afternoon leading to very long lines. They say allow 3 hours before flight time, and IMHO they mean it! The lines are long and slow, and it can start at your airline counter. Only United had a short line; most other carriers had lines snaked in the small terminal at times leading outside the terminal.
After ticketing you must then traverse four more lines, 2 for Aruban authorities and 2 US. The worst line was for US Immigration. Be prepared for standing in lines for 90 minutes or more AFTER getting your boarding pass. My suggestion is be prepared. Have a light meal before you get there since you won't be able to get food until you get to the gate area.
Finally, in the gate area be prepared for a gate change for your flight. Gates are shared amongst all airlines and change based on availability. We saw several last minute changes (including our United flight.) Again - this is for Saturday departures.
Note - the arrival process at Aruba was a breeze.