I have a 770, and have been considering to go for the 800...
But i guess i'm switching.I think the price nokia is selling the 810 is too high for what it is.The good points for the 810 are the form factor, gps and bluetooth...But also has many bad points.
In fact, those good points makes the n7xx/n8xx functionality be reduced to PMP's with GPS, as it has only the benefits of those kind of devices.And that kind of functionality is more or less present on the 770.
Anyway, i think it's a really baaad move from nokia increasing the price on the 810.

About Hildon and so...really, in two years (being VERY pessimistic), we'll be running full-blown linuxes on this kind of devices (the eeePc is just one)...And all the developers have learned about Hildon will be of little or no use, after having suffered a few API changes and all.
Really, making those battery-life-benefits and screen-state benefits transparent to the developer, (in fact , the whole framework) will make the developer base feel better with the platform, instead using their time for more standard devices.