I finally got a Raspberry Pi setup. Took almost 20 minutes to compile nettle, and the configure script figured out not to use neon instructions. It passes the testsuite. Benchmark for the public key functions:
name size sign/ms verify/ms rsa 1024 0.1073 1.9099 rsa 2048 0.0167 0.5539 dsa 1024 0.1992 0.1014 ecdsa 192 0.5297 0.1922 ecdsa 224 0.3623 0.1354 ecdsa 256 0.2621 0.0971 ecdsa 384 0.1125 0.0391 ecdsa 521 0.0551 0.0190
So 3 to 5 times slower than the pandaboard (although that's not a completely fair comparison, since the raspberry pi is using gmp-5.0.5, not the gmp bleeding edge).
Regards, /Niels