Looks like it's available now from A1.net - at least you can order it from the online shop. Actually, the deal looks much better than benny1967 assumed. So you can get the device for €299 with a 24 month contract (€319 minus €20 "online bonus") and €14,50 per month including 100 free minutes and 1GB data traffic (that's €4.50 for the SMART 100 package and €10 for the 1GB data package). You get voice navigation for additional €6 per month.

In related news, the n900 seems to be in store at some Austrian online shops now.

Update: depending on I don't know what, the N900 link on shop.a1.net changes between "Neu bei A1" ("new") and "Demnächst" ("coming soon") between reloads. Don't know what that says about actual availability. Plus, there's a € 49,90 "Aktivierungsentgelt", so the one-time price actually is € 350, at least for new customers.