I doubt there will be really like it in 2009.
Most vendors of "netbooks" go for x86 , the closest I see there is the Raon Digital Everun (aldo still far bigger), but you can see for yourself what a battery live this has...
Edit:
.Gogeta§§J4BR. said:
that's why they have to release the pandora as early as possible... it wouldn't stand a chance against a similar product built around atom-nvidia =`(
I see no indication that it's even remotely possible to build a similar system (I mean by this , same size, same batterylife and "good enough" horsepower to do decent browsing and some other stuff) due power consumption and heat.
/end of edit
For ARM I guess the only "similar" architecture close on the heals is the successor of the nokia N800/810. But this still a good time away afaik and will have most likly a different formfactor. While the N8x0 formfactor has a few things about it, it's not (yet) a "competitor" for the Pandora. We will have to see for the N900.
If you have some other data about ARM devices coming up then please share.
The unique fact of having 2 sd slots giving it lots of storage and a "open" architecture on both software and HW side will still make this things "special" even if "similar" devices come out.
I doubt the Pandora will go "mainstream" but that is also not really the intention.
I do however see a huge potential for "non gamers" power users taking a big interest in this.
Only once example: if your a network admin/dba and need to do standby's ... well I can assure you you really want a thing like this. Got a call fro the boss or some watchdog framework while out? Reach out to your pocket in the pub, connect, vpn / ssh to your system, get the crappy thing back up and order an other pint of beer.
IF the Panordora will deliver what is promised then I think there will be for a good while nothing else on the market that is that flexible on the software front (thankx to OSS) and small with such good battery life specs.