“BogoMips” is a combination of Bogus and Mips. MIPS stands for (depending on who you ask) Millions of Instructions per Second, or Meaningless Indication of Processor Speed.
The number printed at boot time is the result of a kernel timing calibration, used for very short delay loops by some device drivers.
According to the BogoMips mini-HOWTO, the rating for your machine will be:
Common BogoMips Ratings
Processor BogoMips Comparison --------- -------- ---------- Intel 8088 clock * 0.004 0.02 Intel/AMD 386SX clock * 0.14 0.8 Intel/AMD 386DX clock * 0.18 1 (definition) Motorola 68030 clock * 0.25 1.4 Cyrix/IBM 486 clock * 0.34 1.8 Intel Pentium clock * 0.40 2.2 Intel 486 clock * 0.50 2.8 AMD 5x86 clock * 0.50 2.8 Mips R4000/R4400 clock * 0.50 2.8 Nexgen Nx586 clock * 0.75 4.2 PowerPC 601 clock * 0.84 4.7 Alpha 21064/21064A clock * 0.99 5.5 Alpha 21066/21066A clock * 0.99 5.5 Alpha 21164/21164A clock * 0.99 5.5 Intel Pentium Pro clock * 0.99 5.5 Cyrix 5x86/6x86 clock * 1.00 5.6 Intel Pentium II/III clock * 1.00 5.6 Intel Celeron clock * 1.00 5.6 Mips R4600 clock * 1.00 5.6 Alpha 21264 clock * 1.99 11.1 AMD K5/K6/K6-2/K6-III clock * 2.00 11.1 UltraSparc II clock * 2.00 11.1 Pentium MMX clock * 2.00 11.1 PowerPC 604/604e/750 clock * 2.00 11.1 Motorola 68060 clock * 2.01 11.2 Motorola 68040 Not enough data (yet). AMD Athlon Not enough data (yet). IBM S390 Not enough data (yet).
If the number is wildly lower, you may have the Turbo button or CPU speed set incorrectly, or have some kind of caching problem (as described in Why Does the System Slow to a Crawl When Adding More Memory?).
For values people have seen with other, rarer, chips, or to calculate your own BogoMips rating, please refer to the BogoMips Mini-HOWTO, on ftp:// metalab.unc.edu/. See Where Is the Documentation?.