CNET did not review the Fujifilm FinePix S1800, but we did review the, which is very similar.
Both 12-megapixel models feature a Fujinon 18x zoom and 28-504mm-equivalent lens, HD movie recording (720p), mechanical sensor-shift image stabilization, and a 3-inch LCD and electronic viewfinder. The S2550HD, however, has a Mini-HDMI out for connecting directly to an HDTV or monitor, which will cost you roughly $30 more. However, the key components are the same, so we expect that the shooting performance and photo quality would be identical.
The S1800 does have a couple extras to make you think twice about spending the additional money for the S2250HD, though. For some reason only the S1800 comes with automatic picture rotation so you can shoot horizontally or vertically without having to right the images later, and Tracking Auto Focus for keeping moving subjects locked in focus until you're ready to shoot.
The FinePix S2800HD released in the second half of 2010 combines both the features of the S1800 and S2550HD into one model and adds an increase in sensor resolution from 12 to 14 megapixels.