The best news of all is that it comes with Ubuntu, instead of the awful Linpus found on the Acer Aspire One (which still comes with Firefox 2.x). This means we get a modern, well-supported Linux distribution, that's easily updateable and not reliant on whatever Acer doesn't do with it (like updating).
There's more good news, however. The Linux model will sport a significantly lower price tag than the Windows model: GBP 149 vs. GBP 249/299 for the Windows models. The GBP 299 Windows model will come with a Wii-Mote style wireless game-controller-thingie-wachamacallit. Converting these prices to USD or EUR makes for the fun times.
The Revo comes with an Intel Atom 230 processor at 1.6Ghz using NVIDIA's Ion platform, meaning it sports the same GeForce 9400M integrated graphics chipset as found in Apple's MacBooks. Gizmodo tested the thing, and found out that it can play Blu-Ray without any problems, even outputting full HD and 7.1 Dolby over its HDMI port. Anyway, it has 1GB of DDR2 RAM (2GB for the Windows models), and all the usual wireless options.
There is one very important note, however: for now, the Linux model comes with the oh-my-god-please-no 8GB solid state drive, which you really do not want, while the Windows model comes with a 160GB normal HDD. Luckily, Acer has already confirmed that as soon as the Linux/SSD model is sold out, it will immediately be replaced by a Linux model with the same 160GB drive as found in the Windows model, for the same GBP 149 price. That's pretty good news for Linux fans.
In other words, wait until the SSD model is sold out before making your move on this one. Trust me, you do not want the SSD model. The Acer Revo will make its sales debut in the UK on May 5. No information yet available on when it will be on sale in other countries (if you have a link, let us know).